rohrpost

rfc5804.txt (103194B)

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 Internet Engineering Task Force (IETF)                  A. Melnikov, Ed.
 Request for Comments: 5804                                 Isode Limited
 Category: Standards Track                                      T. Martin
 ISSN: 2070-1721                                    BeThereBeSquare, Inc.
                                                                July 2010
 
 
               A Protocol for Remotely Managing Sieve Scripts
 
 Abstract
 
    Sieve scripts allow users to filter incoming email.  Message stores
    are commonly sealed servers so users cannot log into them, yet users
    must be able to update their scripts on them.  This document
    describes a protocol "ManageSieve" for securely managing Sieve
    scripts on a remote server.  This protocol allows a user to have
    multiple scripts, and also alerts a user to syntactically flawed
    scripts.
 
 Status of This Memo
 
    This is an Internet Standards Track document.
 
    This document is a product of the Internet Engineering Task Force
    (IETF).  It represents the consensus of the IETF community.  It has
    received public review and has been approved for publication by the
    Internet Engineering Steering Group (IESG).  Further information on
    Internet Standards is available in Section 2 of RFC 5741.
 
    Information about the current status of this document, any errata,
    and how to provide feedback on it may be obtained at
    http://www.rfc-editor.org/info/rfc5804.
 
 Copyright Notice
 
    Copyright (c) 2010 IETF Trust and the persons identified as the
    document authors.  All rights reserved.
 
    This document is subject to BCP 78 and the IETF Trust's Legal
    Provisions Relating to IETF Documents
    (http://trustee.ietf.org/license-info) in effect on the date of
    publication of this document.  Please review these documents
    carefully, as they describe your rights and restrictions with respect
    to this document.  Code Components extracted from this document must
    include Simplified BSD License text as described in Section 4.e of
    the Trust Legal Provisions and are provided without warranty as
    described in the Simplified BSD License.
 
 
 
 
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 Table of Contents
 
    1. Introduction ....................................................3
       1.1. Commands and Responses .....................................3
       1.2. Syntax .....................................................3
       1.3. Response Codes .............................................3
       1.4. Active Script ..............................................6
       1.5. Quotas .....................................................6
       1.6. Script Names ...............................................6
       1.7. Capabilities ...............................................7
       1.8. Transport ..................................................9
       1.9. Conventions Used in This Document .........................10
    2. Commands .......................................................10
       2.1. AUTHENTICATE Command ......................................11
            2.1.1. Use of SASL PLAIN Mechanism over TLS ...............16
       2.2. STARTTLS Command ..........................................16
            2.2.1. Server Identity Check ..............................17
       2.3. LOGOUT Command ............................................20
       2.4. CAPABILITY Command ........................................20
       2.5. HAVESPACE Command .........................................20
       2.6. PUTSCRIPT Command .........................................21
       2.7. LISTSCRIPTS Command .......................................23
       2.8. SETACTIVE Command .........................................24
       2.9. GETSCRIPT Command .........................................25
       2.10. DELETESCRIPT Command .....................................25
       2.11. RENAMESCRIPT Command .....................................26
       2.12. CHECKSCRIPT Command ......................................27
       2.13. NOOP Command .............................................28
       2.14. Recommended Extensions ...................................28
            2.14.1. UNAUTHENTICATE Command ............................28
    3. Sieve URL Scheme ...............................................29
    4. Formal Syntax ..................................................31
    5. Security Considerations ........................................37
    6. IANA Considerations ............................................38
       6.1. ManageSieve Capability Registration Template ..............39
       6.2. Registration of Initial ManageSieve Capabilities ..........39
       6.3. ManageSieve Response Code Registration Template ...........41
       6.4. Registration of Initial ManageSieve Response Codes ........41
    7. Internationalization Considerations ............................46
    8. Acknowledgements ...............................................46
    9. References .....................................................47
       9.1. Normative References ......................................47
       9.2. Informative References ....................................48
 
 
 
 
 
 
 
 
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 1.  Introduction
 
 1.1.  Commands and Responses
 
    A ManageSieve connection consists of the establishment of a client/
    server network connection, an initial greeting from the server, and
    client/server interactions.  These client/server interactions consist
    of a client command, server data, and a server completion result
    response.
 
    All interactions transmitted by client and server are in the form of
    lines, that is, strings that end with a CRLF.  The protocol receiver
    of a ManageSieve client or server is either reading a line or reading
    a sequence of octets with a known count followed by a line.
 
 1.2.  Syntax
 
    ManageSieve is a line-oriented protocol much like [IMAP] or [ACAP],
    which runs over TCP.  There are three data types: atoms, numbers and
    strings.  Strings may be quoted or literal.  See [ACAP] for detailed
    descriptions of these types.
 
    Each command consists of an atom (the command name) followed by zero
    or more strings and numbers terminated by CRLF.
 
    All client queries are replied to with either an OK, NO, or BYE
    response.  Each response may be followed by a response code (see
    Section 1.3) and by a string consisting of human-readable text in the
    local language (as returned by the LANGUAGE capability; see
    Section 1.7), encoded in UTF-8 [UTF-8].  The contents of the string
    SHOULD be shown to the user ,and implementations MUST NOT attempt to
    parse the message for meaning.
 
    The BYE response SHOULD be used if the server wishes to close the
    connection.  A server may wish to do this because the client was idle
    for too long or there were too many failed authentication attempts.
    This response can be issued at any time and should be immediately
    followed by a server hang-up of the connection.  If a server has an
    inactivity timeout resulting in client autologout, it MUST be no less
    than 30 minutes after successful authentication.  The inactivity
    timeout MAY be less before authentication.
 
 1.3.  Response Codes
 
    An OK, NO, or BYE response from the server MAY contain a response
    code to describe the event in a more detailed machine-parsable
    fashion.  A response code consists of data inside parentheses in the
    form of an atom, possibly followed by a space and arguments.
 
 
 
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    Response codes are defined when there is a specific action that a
    client can take based upon the additional information.  In order to
    support future extension, the response code is represented as a
    slash-separated (Solidus, %x2F) hierarchy with each level of
    hierarchy representing increasing detail about the error.  Response
    codes MUST NOT start with the Solidus character.  Clients MUST
    tolerate additional hierarchical response code detail that they don't
    understand.  For example, if the client supports the "QUOTA" response
    code, but doesn't understand the "QUOTA/MAXSCRIPTS" response code, it
    should treat "QUOTA/MAXSCRIPTS" as "QUOTA".
 
    Client implementations MUST tolerate (ignore) response codes that
    they do not recognize.
 
    The currently defined response codes are the following:
 
    AUTH-TOO-WEAK
 
    This response code is returned in the NO or BYE response from an
    AUTHENTICATE command.  It indicates that site security policy forbids
    the use of the requested mechanism for the specified authentication
    identity.
 
    ENCRYPT-NEEDED
 
    This response code is returned in the NO or BYE response from an
    AUTHENTICATE command.  It indicates that site security policy
    requires the use of a strong encryption mechanism for the specified
    authentication identity and mechanism.
 
    QUOTA
 
    If this response code is returned in the NO/BYE response, it means
    that the command would have placed the user above the site-defined
    quota constraints.  If this response code is returned in the OK
    response, it can mean that the user's storage is near its quota, or
    it can mean that the account exceeded its quota but that the
    condition is being allowed by the server (the server supports
    so-called soft quotas).  The QUOTA response code has two more
    detailed variants: "QUOTA/MAXSCRIPTS" (the maximum number of per-user
    scripts) and "QUOTA/MAXSIZE" (the maximum script size).
 
    REFERRAL
 
    This response code may be returned with a BYE result from any
    command, and includes a mandatory parameter that indicates what
    server to access to manage this user's Sieve scripts.  The server
    will be specified by a Sieve URL (see Section 3).  The scriptname
 
 
 
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    portion of the URL MUST NOT be specified.  The client should
    authenticate to the specified server and use it for all further
    commands in the current session.
 
    SASL
 
    This response code can occur in the OK response to a successful
    AUTHENTICATE command and includes the optional final server response
    data from the server as specified by [SASL].
 
    TRANSITION-NEEDED
 
    This response code occurs in a NO response of an AUTHENTICATE
    command.  It indicates that the user name is valid, but the entry in
    the authentication database needs to be updated in order to permit
    authentication with the specified mechanism.  This is typically done
    by establishing a secure channel using TLS, verifying server identity
    as specified in Section 2.2.1, and finally authenticating once using
    the [PLAIN] authentication mechanism.  The selected mechanism SHOULD
    then work for authentications in subsequent sessions.
 
    This condition can happen if a user has an entry in a system
    authentication database such as Unix /etc/passwd, but does not have
    credentials suitable for use by the specified mechanism.
 
    TRYLATER
 
    A command failed due to a temporary server failure.  The client MAY
    continue using local information and try the command later.  This
    response code only makes sense when returned in a NO/BYE response.
 
    ACTIVE
 
    A command failed because it is not allowed on the active script, for
    example, DELETESCRIPT on the active script.  This response code only
    makes sense when returned in a NO/BYE response.
 
    NONEXISTENT
 
    A command failed because the referenced script name doesn't exist.
    This response code only makes sense when returned in a NO/BYE
    response.
 
    ALREADYEXISTS
 
    A command failed because the referenced script name already exists.
    This response code only makes sense when returned in a NO/BYE
    response.
 
 
 
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    TAG
 
    This response code name is followed by a string specified in the
    command.  See Section 2.13 for a possible use case.
 
    WARNINGS
 
    This response code MAY be returned by the server in the OK response
    (but it might be returned with the NO/BYE response as well) and
    signals the client that even though the script is syntactically
    valid, it might contain errors not intended by the script writer.
    This response code is typically returned in response to PUTSCRIPT
    and/or CHECKSCRIPT commands.  A client seeing such response code
    SHOULD present the returned warning text to the user.
 
 1.4.  Active Script
 
    A user may have multiple Sieve scripts on the server, yet only one
    script may be used for filtering of incoming messages.  This is the
    active script.  Users may have zero or one active script and MUST use
    the SETACTIVE command described below for changing the active script
    or disabling Sieve processing.  For example, users may have an
    everyday script they normally use and a special script they use when
    they go on vacation.  Users can change which script is being used
    without having to download and upload a script stored somewhere else.
 
 1.5.  Quotas
 
    Servers SHOULD impose quotas to prevent malicious users from
    overflowing available storage.  If a command would place a user over
    a quota setting, servers that impose such quotas MUST reply with a NO
    response containing the QUOTA response code.  Client implementations
    MUST be able to handle commands failing because of quota
    restrictions.
 
 1.6.  Script Names
 
    A Sieve script name is a sequence of Unicode characters encoded in
    UTF-8 [UTF-8].  A script name MUST comply with Net-Unicode Definition
    (Section 2 of [NET-UNICODE]), with the additional restriction of
    prohibiting the following Unicode characters:
 
    o  0000-001F; [CONTROL CHARACTERS]
 
    o  007F; DELETE
 
    o  0080-009F; [CONTROL CHARACTERS]
 
 
 
 
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    o  2028; LINE SEPARATOR
 
    o  2029; PARAGRAPH SEPARATOR
 
    Sieve script names MUST be at least one octet (and hence Unicode
    character) long.  Zero octets script name has a special meaning (see
    Section 2.8).  Servers MUST allow names of up to 128 Unicode
    characters in length (which can take up to 512 bytes when encoded in
    UTF-8, not counting the terminating NUL), and MAY allow longer names.
    A server that receives a script name longer than its internal limit
    MUST reject the corresponding operation, in particular it MUST NOT
    truncate the script name.
 
 1.7.  Capabilities
 
    Server capabilities are sent automatically by the server upon a
    client connection, or after successful STARTTLS and AUTHENTICATE
    (which establishes a Simple Authentication and Security Layer (SASL))
    commands.  Capabilities may change immediately after a successfully
    completed STARTTLS command, and/or immediately after a successfully
    completed AUTHENTICATE command, and/or after a successfully completed
    UNAUTHENTICATE command (see Section 2.14.1).  Capabilities MUST
    remain static at all other times.
 
    Clients MAY request the capabilities at a later time by issuing the
    CAPABILITY command described later.  The capabilities consist of a
    series of lines each with one or two strings.  The first string is
    the name of the capability, which is case-insensitive.  The second
    optional string is the value associated with that capability.  Order
    of capabilities is arbitrary, but each capability name can appear at
    most once.
 
    The following capabilities are defined in this document:
 
    IMPLEMENTATION - Name of implementation and version.  This capability
    MUST always be returned by the server.
 
    SASL - List of SASL mechanisms supported by the server, each
    separated by a space.  This list can be empty if and only if STARTTLS
    is also advertised.  This means that the client must negotiate TLS
    encryption with STARTTLS first, at which point the SASL capability
    will list a non-empty list of SASL mechanisms.
 
    SIEVE - List of space-separated Sieve extensions (as listed in Sieve
    "require" action [SIEVE]) supported by the Sieve engine.  This
    capability MUST always be returned by the server.
 
 
 
 
 
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    STARTTLS - If TLS [TLS] is supported by this implementation.  Before
    advertising this capability a server MUST verify to the best of its
    ability that TLS can be successfully negotiated by a client with
    common cipher suites.  Specifically, a server should verify that a
    server certificate has been installed and that the TLS subsystem has
    successfully initialized.  This capability SHOULD NOT be advertised
    once STARTTLS or AUTHENTICATE command completes successfully.  Client
    and server implementations MUST implement the STARTTLS extension.
 
    MAXREDIRECTS - Specifies the limit on the number of Sieve "redirect"
    actions a script can perform during a single evaluation.  Note that
    this is different from the total number of "redirect" actions a
    script can contain.  The value is a non-negative number represented
    as a ManageSieve string.
 
    NOTIFY - A space-separated list of URI schema parts for supported
    notification methods.  This capability MUST be specified if the Sieve
    implementation supports the "enotify" extension [NOTIFY].
 
    LANGUAGE - The language (<Language-Tag> from [RFC5646]) currently
    used for human-readable error messages.  If this capability is not
    returned, the "i-default" [RFC2277] language is assumed.  Note that
    the current language MAY be per-user configurable (i.e., it MAY
    change after authentication).
 
    OWNER - The canonical name of the logged-in user (SASL "authorization
    identity") encoded in UTF-8.  This capability MUST NOT be returned in
    unauthenticated state and SHOULD be returned once the AUTHENTICATE
    command succeeds.
 
    VERSION - This capability MUST be returned by servers compliant with
    this document or its successor.  For servers compliant with this
    document, the capability value is the string "1.0".  Lack of this
    capability means that the server predates this specification and thus
    doesn't support the following commands: RENAMESCRIPT, CHECKSCRIPT,
    and NOOP.
 
    Section 2.14 defines some additional ManageSieve extensions and their
    respective capabilities.
 
    A server implementation MUST return SIEVE, IMPLEMENTATION, and
    VERSION capabilities.
 
    A client implementation MUST ignore any listed capabilities that it
    does not understand.
 
 
 
 
 
 
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        Example:
 
        S: "IMPlemENTATION" "Example1 ManageSieved v001"
        S: "SASl" "DIGEST-MD5 GSSAPI"
        S: "SIeVE" "fileinto vacation"
        S: "StaRTTLS"
        S: "NOTIFY" "xmpp mailto"
        S: "MAXREdIRECTS" "5"
        S: "VERSION" "1.0"
        S: OK
 
    After successful authentication, this might look like this:
 
        Example:
 
        S: "IMPlemENTATION" "Example1 ManageSieved v001"
        S: "SASl" "DIGEST-MD5 GSSAPI"
        S: "SIeVE" "fileinto vacation"
        S: "NOTIFY" "xmpp mailto"
        S: "OWNER" "alexey@example.com"
        S: "MAXREdIRECTS" "5"
        S: "VERSION" "1.0"
        S: OK
 
 1.8.  Transport
 
    The ManageSieve protocol assumes a reliable data stream such as that
    provided by TCP.  When TCP is used, a ManageSieve server typically
    listens on port 4190.
 
    Before opening the TCP connection, the ManageSieve client first MUST
    resolve the Domain Name System (DNS) hostname associated with the
    receiving entity and determine the appropriate TCP port for
    communication with the receiving entity.  The process is as follows:
 
    1.  Attempt to resolve the hostname using a [DNS-SRV] Service of
        "sieve" and a Proto of "tcp" for the target domain (e.g.,
        "example.net"), resulting in resource records such as
        "_sieve._tcp.example.net.".  The result of the SRV lookup, if
        successful, will be one or more combinations of a port and
        hostname; the ManageSieve client MUST resolve the returned
        hostnames to IPv4/IPv6 addresses according to returned SRV record
        weight.  IP addresses from the first successfully resolved
        hostname (with the corresponding port number returned by SRV
        lookup) are used to connect to the server.  If connection using
        one of the IP addresses fails, the next resolved IP address is
 
 
 
 
 
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        used to connect.  If connection to all resolved IP addresses
        fails, then the resolution/connect is repeated for the next
        hostname returned by SRV lookup.
 
    2.  If the SRV lookup fails, the fallback SHOULD be a normal IPv4 or
        IPv6 address record resolution to determine the IP address, where
        the port used is the default ManageSieve port of 4190.
 
 1.9.  Conventions Used in This Document
 
    The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
    "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
    document are to be interpreted as described in [KEYWORDS].
 
    In examples, "C:" and "S:" indicate lines sent by the client and
    server respectively.  Line breaks that do not start a new "C:" or
    "S:" exist for editorial reasons.
 
    Examples of authentication in this document are using DIGEST-MD5
    [DIGEST-MD5] and GSSAPI [GSSAPI] SASL mechanisms.
 
 2.  Commands
 
    This section and its subsections describe valid ManageSieve commands.
    Upon initial connection to the server, the client's session is in
    non-authenticated state.  Prior to successful authentication, only
    the AUTHENTICATE, CAPABILITY, STARTTLS, LOGOUT, and NOOP (see Section
    2.13) commands are valid.  ManageSieve extensions MAY define other
    commands that are valid in non-authenticated state.  Servers MUST
    reject all other commands with a NO response.  Clients may pipeline
    commands (send more than one command at a time without waiting for
    completion of the first command).  However, a group of commands sent
    together MUST NOT have an AUTHENTICATE (*), a STARTTLS, or a
    HAVESPACE command anywhere but the last command in the list.
 
    (*) - The only exception to this rule is when the AUTHENTICATE
    command contains an initial response for a SASL mechanism that allows
    clients to send data first, the mechanism is known to complete in one
    round trip, and the mechanism doesn't negotiate a SASL security
    layer.  Two examples of such SASL mechanisms are PLAIN [PLAIN] and
    EXTERNAL [SASL].
 
 
 
 
 
 
 
 
 
 
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 2.1.  AUTHENTICATE Command
 
    Arguments:  String - mechanism
                String - initial data (optional)
 
    The AUTHENTICATE command indicates a SASL [SASL] authentication
    mechanism to the server.  If the server supports the requested
    authentication mechanism, it performs an authentication protocol
    exchange to identify and authenticate the user.  Optionally, it also
    negotiates a security layer for subsequent protocol interactions.  If
    the requested authentication mechanism is not supported, the server
    rejects the AUTHENTICATE command by sending the NO response.
 
    The authentication protocol exchange consists of a series of server
    challenges and client responses that are specific to the selected
    authentication mechanism.  A server challenge consists of a string
    (quoted or literal) followed by a CRLF.  The contents of the string
    is a base-64 encoding [BASE64] of the SASL data.  A client response
    consists of a string (quoted or literal) with the base-64 encoding of
    the SASL data followed by a CRLF.  If the client wishes to cancel the
    authentication exchange, it issues a string containing a single "*".
    If the server receives such a response, it MUST reject the
    AUTHENTICATE command by sending a NO reply.
 
    Note that an empty challenge/response is sent as an empty string.  If
    the mechanism dictates that the final response is sent by the server,
    this data MAY be placed within the data portion of the SASL response
    code to save a round trip.
 
    The optional initial-response argument to the AUTHENTICATE command is
    used to save a round trip when using authentication mechanisms that
    are defined to send no data in the initial challenge.  When the
    initial-response argument is used with such a mechanism, the initial
    empty challenge is not sent to the client and the server uses the
    data in the initial-response argument as if it were sent in response
    to the empty challenge.  If the initial-response argument to the
    AUTHENTICATE command is used with a mechanism that sends data in the
    initial challenge, the server MUST reject the AUTHENTICATE command by
    sending the NO response.
 
    The service name specified by this protocol's profile of SASL is
    "sieve".
 
    Reauthentication is not supported by ManageSieve protocol's profile
    of SASL.  That is, after a successfully completed AUTHENTICATE
    command, no more AUTHENTICATE commands may be issued in the same
    session.  After a successful AUTHENTICATE command completes, a server
    MUST reject any further AUTHENTICATE commands with a NO reply.
 
 
 
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    However, note that a server may implement the UNAUTHENTICATE
    extension described in Section 2.14.1.
 
    If a security layer is negotiated through the SASL authentication
    exchange, it takes effect immediately following the CRLF that
    concludes the successful authentication exchange for the client, and
    the CRLF of the OK response for the server.
 
    When a security layer takes effect, the ManageSieve protocol is reset
    to the initial state (the state in ManageSieve after a client has
    connected to the server).  The server MUST discard any knowledge
    obtained from the client that was not obtained from the SASL (or TLS)
    negotiation itself.  Likewise, the client MUST discard any knowledge
    obtained from the server, such as the list of ManageSieve extensions,
    that was not obtained from the SASL (and/or TLS) negotiation itself.
    (Note that a client MAY compare the advertised SASL mechanisms before
    and after authentication in order to detect an active down-
    negotiation attack.  See below.)
 
    Once a SASL security layer is established, the server MUST re-issue
    the capability results, followed by an OK response.  This is
    necessary to protect against man-in-the-middle attacks that alter the
    capabilities list prior to SASL negotiation.  The capability results
    MUST include all SASL mechanisms the server was capable of
    negotiating with that client.  This is done in order to allow the
    client to detect an active down-negotiation attack.  If a user-
    oriented client detects such a down-negotiation attack, it SHOULD
    either notify the user (it MAY give the user the opportunity to
    continue with the ManageSieve session in this case) or close the
    transport connection and indicate that a down-negotiation attack
    might be in progress.  If an automated client detects a down-
    negotiation attack, it SHOULD return or log an error indicating that
    a possible attack might be in progress and/or SHOULD close the
    transport connection.
 
    When both [TLS] and SASL security layers are in effect, the TLS
    encoding MUST be applied (when sending data) after the SASL encoding.
 
    Server implementations SHOULD support SASL proxy authentication so
    that an administrator can administer a user's scripts.  Proxy
    authentication is when a user authenticates as herself/himself but
    requests the server to act (authorize) as another user.
 
    The authorization identity generated by this [SASL] exchange is a
    "simple username" (in the sense defined in [SASLprep]), and both
    client and server MUST use the [SASLprep] profile of the [StringPrep]
    algorithm to prepare these names for transmission or comparison.  If
    preparation of the authorization identity fails or results in an
 
 
 
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    empty string (unless it was transmitted as the empty string), the
    server MUST fail the authentication.
 
    If an AUTHENTICATE command fails with a NO response, the client MAY
    try another authentication mechanism by issuing another AUTHENTICATE
    command.  In other words, the client may request authentication types
    in decreasing order of preference.
 
    Note that a failed (NO) response to the AUTHENTICATE command may
    contain one of the following response codes: AUTH-TOO-WEAK, ENCRYPT-
    NEEDED, or TRANSITION-NEEDED.  See Section 1.3 for detailed
    description of the relevant conditions.
 
    To ensure interoperability, both client and server implementations of
    the ManageSieve protocol MUST implement the SCRAM-SHA-1 [SCRAM] SASL
    mechanism, as well as [PLAIN] over [TLS].
 
    Note: use of PLAIN over TLS reflects current use of PLAIN over TLS in
    other email-related protocols; however, a longer-term goal is to
    migrate email-related protocols from using PLAIN over TLS to SCRAM-
    SHA-1 mechanism.
 
    Examples (Note that long lines are folded for readability and are not
    part of protocol exchange):
 
        S: "IMPLEMENTATION" "Example1 ManageSieved v001"
        S: "SASL" "DIGEST-MD5 GSSAPI"
        S: "SIEVE" "fileinto vacation"
        S: "STARTTLS"
        S: "VERSION" "1.0"
        S: OK
        C: Authenticate "DIGEST-MD5"
        S: "cmVhbG09ImVsd29vZC5pbm5vc29mdC5leGFtcGxlLmNvbSIsbm9uY2U9Ik
           9BNk1HOXRFUUdtMmhoIixxb3A9ImF1dGgiLGFsZ29yaXRobT1tZDUtc2Vz
           cyxjaGFyc2V0PXV0Zi04"
        C: "Y2hhcnNldD11dGYtOCx1c2VybmFtZT0iY2hyaXMiLHJlYWxtPSJlbHdvb2
           QuaW5ub3NvZnQuZXhhbXBsZS5jb20iLG5vbmNlPSJPQTZNRzl0RVFHbTJo
           aCIsbmM9MDAwMDAwMDEsY25vbmNlPSJPQTZNSFhoNlZxVHJSayIsZGlnZX
           N0LXVyaT0ic2lldmUvZWx3b29kLmlubm9zb2Z0LmV4YW1wbGUuY29tIixy
           ZXNwb25zZT1kMzg4ZGFkOTBkNGJiZDc2MGExNTIzMjFmMjE0M2FmNyxxb3
           A9YXV0aA=="
        S: OK (SASL "cnNwYXV0aD1lYTQwZjYwMzM1YzQyN2I1NTI3Yjg0ZGJhYmNkZ
           mZmZA==")
 
 
 
 
 
 
 
 
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    A slightly different variant of the same authentication exchange is:
 
        S: "IMPLEMENTATION" "Example1 ManageSieved v001"
        S: "SASL" "DIGEST-MD5 GSSAPI"
        S: "SIEVE" "fileinto vacation"
        S: "VERSION" "1.0"
        S: "STARTTLS"
        S: OK
        C: Authenticate "DIGEST-MD5"
        S: {136}
        S: cmVhbG09ImVsd29vZC5pbm5vc29mdC5leGFtcGxlLmNvbSIsbm9uY2U9Ik
           9BNk1HOXRFUUdtMmhoIixxb3A9ImF1dGgiLGFsZ29yaXRobT1tZDUtc2Vz
           cyxjaGFyc2V0PXV0Zi04
        C: {300+}
        C: Y2hhcnNldD11dGYtOCx1c2VybmFtZT0iY2hyaXMiLHJlYWxtPSJlbHdvb2
           QuaW5ub3NvZnQuZXhhbXBsZS5jb20iLG5vbmNlPSJPQTZNRzl0RVFHbTJo
           aCIsbmM9MDAwMDAwMDEsY25vbmNlPSJPQTZNSFhoNlZxVHJSayIsZGlnZX
           N0LXVyaT0ic2lldmUvZWx3b29kLmlubm9zb2Z0LmV4YW1wbGUuY29tIixy
           ZXNwb25zZT1kMzg4ZGFkOTBkNGJiZDc2MGExNTIzMjFmMjE0M2FmNyxxb3
           A9YXV0aA==
        S: {56}
        S: cnNwYXV0aD1lYTQwZjYwMzM1YzQyN2I1NTI3Yjg0ZGJhYmNkZmZmZA==
        C: ""
        S: OK
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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    Another example demonstrating use of SASL PLAIN mechanism under TLS
    follows.  This example also demonstrate use of SASL "initial
    response" (the second parameter to the Authenticate command):
 
        S: "IMPLEMENTATION" "Example1 ManageSieved v001"
        S: "VERSION" "1.0"
        S: "SASL" ""
        S: "SIEVE" "fileinto vacation"
        S: "STARTTLS"
        S: OK
        C: STARTTLS
        S: OK
        <TLS negotiation, further commands are under TLS layer>
        S: "IMPLEMENTATION" "Example1 ManageSieved v001"
        S: "VERSION" "1.0"
        S: "SASL" "PLAIN"
        S: "SIEVE" "fileinto vacation"
        S: OK
        C: Authenticate "PLAIN" "QJIrweAPyo6Q1T9xu"
        S: NO
        C: Authenticate "PLAIN" "QJIrweAPyo6Q1T9xz"
        S: NO
        C: Authenticate "PLAIN" "QJIrweAPyo6Q1T9xy"
        S: BYE "Too many failed authentication attempts"
        <Server closes connection>
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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    The following example demonstrates use of SASL "initial response".
    It also demonstrates that an empty response can be sent as a literal
    and that negotiating a SASL security layer results in the server
    re-issuing server capabilities:
 
        C: AUTHENTICATE "GSSAPI" {1488+}
        C: YIIE[...1480 octets here ...]dA==
        S: {208}
        S: YIGZBgkqhkiG9xIBAgICAG+BiTCBhqADAgEFoQMCAQ+iejB4oAMCARKic
           [...114 octets here ...]
           /yzpAy9p+Y0LanLskOTvMc0MnjgAa4YEr3eJ6
        C: {0+}
        C:
        S: {44}
        S: BQQF/wAMAAwAAAAAYRGFAo6W0vIHti8i1UXODgEAEAA=
        C: {44+}
        C: BQQE/wAMAAwAAAAAIsT1iv9UkZApw471iXt6cwEAAAE=
        S: OK
        <Further commands/responses are under SASL security layer>
        S: "IMPLEMENTATION" "Example1 ManageSieved v001"
        S: "VERSION" "1.0"
        S: "SASL" "PLAIN DIGEST-MD5 GSSAPI"
        S: "SIEVE" "fileinto vacation"
        S: "LANGUAGE" "ru"
        S: "MAXREDIRECTS" "3"
        S: ok
 
 2.1.1.  Use of SASL PLAIN Mechanism over TLS
 
    This section is normative for ManageSieve client implementations that
    support SASL [PLAIN] over [TLS].
 
    If a ManageSieve client is willing to use SASL PLAIN over TLS to
    authenticate to the ManageSieve server, the client MUST verify the
    server identity (see Section 2.2.1).  If the server identity can't be
    verified (e.g., the server has not provided any certificate, or if
    the certificate verification fails), the client MUST NOT attempt to
    authenticate using the SASL PLAIN mechanism.
 
 2.2.  STARTTLS Command
 
    Support for STARTTLS command in servers is optional.  Its
    availability is advertised with "STARTTLS" capability as described in
    Section 1.7.
 
    The STARTTLS command requests commencement of a TLS [TLS]
    negotiation.  The negotiation begins immediately after the CRLF in
    the OK response.  After a client issues a STARTTLS command, it MUST
 
 
 
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    NOT issue further commands until a server response is seen and the
    TLS negotiation is complete.
 
    The STARTTLS command is only valid in non-authenticated state.  The
    server remains in non-authenticated state, even if client credentials
    are supplied during the TLS negotiation.  The SASL [SASL] EXTERNAL
    mechanism MAY be used to authenticate once TLS client credentials are
    successfully exchanged, but servers supporting the STARTTLS command
    are not required to support the EXTERNAL mechanism.
 
    After the TLS layer is established, the server MUST re-issue the
    capability results, followed by an OK response.  This is necessary to
    protect against man-in-the-middle attacks that alter the capabilities
    list prior to STARTTLS.  This capability result MUST NOT include the
    STARTTLS capability.
 
    The client MUST discard cached capability information and replace it
    with the new information.  The server MAY advertise different
    capabilities after STARTTLS.
 
        Example:
 
        C: StartTls
        S: oK
        <TLS negotiation, further commands are under TLS layer>
        S: "IMPLEMENTATION" "Example1 ManageSieved v001"
        S: "SASL" "PLAIN DIGEST-MD5 GSSAPI"
        S: "SIEVE" "fileinto vacation"
        S: "VERSION" "1.0"
        S: "LANGUAGE" "fr"
        S: ok
 
 2.2.1.  Server Identity Check
 
    During the TLS negotiation, the ManageSieve client MUST check its
    understanding of the server hostname/IP address against the server's
    identity as presented in the server Certificate message, in order to
    prevent man-in-the-middle attacks.  In this section, the client's
    understanding of the server's identity is called the "reference
    identity".
 
    Checking is performed according to the following rules:
 
    o  If the reference identity is a hostname:
 
       1.  If a subjectAltName extension of the SRVName [X509-SRV],
           dNSName [X509] (in that order of preference) type is present
           in the server's certificate, then it SHOULD be used as the
 
 
 
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           source of the server's identity.  Matching is performed as
           described in Section 2.2.1.1, with the exception that no
           wildcard matching is allowed for SRVName type.  If the
           certificate contains multiple names (e.g., more than one
           dNSName field), then a match with any one of the fields is
           considered acceptable.
 
       2.  The client MAY use other types of subjectAltName for
           performing comparison.
 
       3.  The server's identity MAY also be verified by comparing the
           reference identity to the Common Name (CN) [RFC4519] value in
           the leaf Relative Distinguished Name (RDN) of the subjectName
           field of the server's certificate.  This comparison is
           performed using the rules for comparison of DNS names in
           Section 2.2.1.1, below.  Although the use of the Common Name
           value is existing practice, it is deprecated, and
           Certification Authorities are encouraged to provide
           subjectAltName values instead.  Note that the TLS
           implementation may represent DNs in certificates according to
           X.500 or other conventions.  For example, some X.500
           implementations order the RDNs in a DN using a left-to-right
           (most significant to least significant) convention instead of
           LDAP's right-to-left convention.
 
    o  When the reference identity is an IP address, the iPAddress
       subjectAltName SHOULD be used by the client for comparison.  The
       comparison is performed as described in Section 2.2.1.2.
 
    If the server identity check fails, user-oriented clients SHOULD
    either notify the user (clients MAY give the user the opportunity to
    continue with the ManageSieve session in this case) or close the
    transport connection and indicate that the server's identity is
    suspect.  Automated clients SHOULD return or log an error indicating
    that the server's identity is suspect and/or SHOULD close the
    transport connection.  Automated clients MAY provide a configuration
    setting that disables this check, but MUST provide a setting that
    enables it.
 
    Beyond the server identity check described in this section, clients
    should be prepared to do further checking to ensure that the server
    is authorized to provide the service it is requested to provide.  The
    client may need to make use of local policy information in making
    this determination.
 
 
 
 
 
 
 
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 2.2.1.1.  Comparison of DNS Names
 
    If the reference identity is an internationalized domain name,
    conforming implementations MUST convert it to the ASCII Compatible
    Encoding (ACE) format as specified in Section 4 of RFC 3490 [RFC3490]
    before comparison with subjectAltName values of type dNSName.
    Specifically, conforming implementations MUST perform the conversion
    operation specified in Section 4 of [RFC3490] as follows:
 
    o  in step 1, the domain name SHALL be considered a "stored string";
 
    o  in step 3, set the flag called "UseSTD3ASCIIRules";
 
    o  in step 4, process each label with the "ToASCII" operation; and
 
    o  in step 5, change all label separators to U+002E (full stop).
 
    After performing the "to-ASCII" conversion, the DNS labels and names
    MUST be compared for equality according to the rules specified in
    Section 3 of [RFC3490]; i.e., once all label separators are replaced
    with U+002E (dot) they are compared in the case-insensitive manner.
 
    The '*' (ASCII 42) wildcard character is allowed in subjectAltName
    values of type dNSName, and then only as the left-most (least
    significant) DNS label in that value.  This wildcard matches any
    left-most DNS label in the server name.  That is, the subject
    *.example.com matches the server names a.example.com and
    b.example.com, but does not match example.com or a.b.example.com.
 
 2.2.1.2.  Comparison of IP Addresses
 
    When the reference identity is an IP address, the identity MUST be
    converted to the "network byte order" octet string representation
    [RFC791][RFC2460].  For IP Version 4, as specified in RFC 791, the
    octet string will contain exactly four octets.  For IP Version 6, as
    specified in RFC 2460, the octet string will contain exactly sixteen
    octets.  This octet string is then compared against subjectAltName
    values of type iPAddress.  A match occurs if the reference identity
    octet string and value octet strings are identical.
 
 2.2.1.3.  Comparison of Other subjectName Types
 
    Client implementations MAY support matching against subjectAltName
    values of other types as described in other documents.
 
 
 
 
 
 
 
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 2.3.  LOGOUT Command
 
    The client sends the LOGOUT command when it is finished with a
    connection and wishes to terminate it.  The server MUST reply with an
    OK response.  The server MUST ignore commands issued by the client
    after the LOGOUT command.
 
    The client SHOULD wait for the OK response before closing the
    connection.  This avoids the TCP connection going into the TIME_WAIT
    state on the server.  In order to avoid going into the TIME_WAIT TCP
    state, the server MAY wait for a short while for the client to close
    the TCP connection first.  Whether or not the server waits for the
    client to close the connection, it MUST then close the connection
    itself.
 
        Example:
 
        C: Logout
        S: Ok
        <connection is terminated>
 
 2.4.  CAPABILITY Command
 
    The CAPABILITY command requests the server capabilities as described
    earlier in this document.  It has no parameters.
 
        Example:
 
        C: CAPABILITY
        S: "IMPLEMENTATION" "Example1 ManageSieved v001"
        S: "VERSION" "1.0"
        S: "SASL" "PLAIN SCRAM-SHA-1 GSSAPI"
        S: "SIEVE" "fileinto vacation"
        S: "STARTTLS"
        S: OK
 
 2.5.  HAVESPACE Command
 
    Arguments:  String - name
                Number - script size
 
    The HAVESPACE command is used to query the server for available
    space.  Clients specify the name they wish to save the script as and
    its size in octets.  Both parameters can be used by the server to see
    if the script with the specified name and size is within a user's
    quota(s).  For example, the server MAY use the script name to check
    if a script would be replaced or a new one would be created.  Servers
    respond with a NO if storing a script with that name and size would
 
 
 
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    fail or OK otherwise.  Clients SHOULD issue this command before
    attempting to place a script on the server.
 
    Note that the OK response from the HAVESPACE command does not
    constitute a guarantee of success as server disk space conditions
    could change between the client issuing the HAVESPACE and the client
    issuing the PUTSCRIPT commands.  A QUOTA response code (see
    Section 1.3) remains a possible (albeit unlikely) response to a
    subsequent PUTSCRIPT with the same name and size.
 
        Example:
 
        C: HAVESPACE "myscript" 999999
        S: NO (QUOTA/MAXSIZE) "Quota exceeded"
 
        C: HAVESPACE "foobar" 435
        S: OK
 
 2.6.  PUTSCRIPT Command
 
    Arguments:  String - Script name
                String - Script content
 
    The PUTSCRIPT command is used by the client to submit a Sieve script
    to the server.
 
    If the script already exists, upon success the old script will be
    overwritten.  The old script MUST NOT be overwritten if PUTSCRIPT
    fails in any way.  A script of zero length SHOULD be disallowed.
 
    This command places the script on the server.  It does not affect
    whether the script is processed on incoming mail, unless it replaces
    the script that is already active.  The SETACTIVE command is used to
    mark a script as active.
 
    When submitting large scripts, clients SHOULD use the HAVESPACE
    command beforehand to query if the server is willing to accept a
    script of that size.
 
    The server MUST check the submitted script for validity, which
    includes checking that the script complies with the Sieve grammar
    [SIEVE] and that all Sieve extensions mentioned in the script's
    "require" statement(s) are supported by the Sieve interpreter.  (Note
    that if the Sieve interpreter supports the Sieve "ihave" extension
    [I-HAVE], any unrecognized/unsupported extension mentioned in the
    "ihave" test MUST NOT cause the validation failure.)  Other checks
    such as validating the supplied command arguments for each command
    MAY be performed.  Essentially, the performed validation SHOULD be
 
 
 
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    the same as performed when compiling the script for execution.
    Implementations that use a binary representation to store compiled
    scripts can extend the validation to a full compilation, in order to
    avoid validating uploaded scripts multiple times.
 
    If the script fails the validation, the server MUST reply with a NO
    response.  Any script that fails the validity test MUST NOT be stored
    on the server.  The message given with a NO response MUST be human
    readable and SHOULD contain a specific error message giving the line
    number of the first error.  Implementors should strive to produce
    helpful error messages similar to those given by programming language
    compilers.  Client implementations should note that this may be a
    multiline literal string with more than one error message separated
    by CRLFs.  The human-readable message is in the language returned in
    the latest LANGUAGE capability (or in "i-default"; see Section 1.7),
    encoded in UTF-8 [UTF-8].
 
    An OK response MAY contain the WARNINGS response code.  In such a
    case the human-readable message that follows the OK response SHOULD
    contain a specific warning message (or messages) giving the line
    number(s) in the script that might contain errors not intended by the
    script writer.  The human-readable message is in the language
    returned in the latest LANGUAGE capability (or in "i-default"; see
    Section 1.7), encoded in UTF-8 [UTF-8].  A client seeing such a
    response code SHOULD present the message to the user.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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        Examples:
 
        C: Putscript "foo" {31+}
        C: #comment
        C: InvalidSieveCommand
        C:
        S: NO "line 2: Syntax error"
 
        C: Putscript "mysievescript" {110+}
        C: require ["fileinto"];
        C:
        C: if envelope :contains "to" "tmartin+sent" {
        C:   fileinto "INBOX.sent";
        C: }
        S: OK
 
        C: Putscript "myforwards" {190+}
        C: redirect "111@example.net";
        C:
        C: if size :under 10k {
        C:     redirect "mobile@cell.example.com";
        C: }
        C:
        C: if envelope :contains "to" "tmartin+lists" {
        C:     redirect "lists@groups.example.com";
        C: }
        S: OK (WARNINGS) "line 8: server redirect action
                limit is 2, this redirect might be ignored"
 
 2.7.  LISTSCRIPTS Command
 
    This command lists the scripts the user has on the server.  Upon
    success, a list of CRLF-separated script names (each represented as a
    quoted or literal string) is returned followed by an OK response.  If
    there exists an active script, the atom ACTIVE is appended to the
    corresponding script name.  The atom ACTIVE MUST NOT appear on more
    than one response line.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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        Example:
 
        C: Listscripts
        S: "summer_script"
        S: "vacation_script"
        S: {13}
        S: clever"script
        S: "main_script" ACTIVE
        S: OK
 
        C: listscripts
        S: "summer_script"
        S: "main_script" active
        S: OK
 
 2.8.  SETACTIVE Command
 
    Arguments:  String - script name
 
    This command sets a script active.  If the script name is the empty
    string (i.e., ""), then any active script is disabled.  Disabling an
    active script when there is no script active is not an error and MUST
    result in an OK reply.
 
    If the script does not exist on the server, then the server MUST
    reply with a NO response.  Such a reply SHOULD contain the
    NONEXISTENT response code.
 
        Examples:
 
        C: Setactive "vacationscript"
        S: Ok
 
        C: Setactive ""
        S: Ok
 
        C: Setactive "baz"
        S: No (NONEXISTENT) "There is no script by that name"
 
        C: Setactive "baz"
        S: No (NONEXISTENT) {31}
        S: There is no script by that name
 
 
 
 
 
 
 
 
 
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 2.9.  GETSCRIPT Command
 
    Arguments:  String - script name
 
    This command gets the contents of the specified script.  If the
    script does not exist, the server MUST reply with a NO response.
    Such a reply SHOULD contain the NONEXISTENT response code.
 
    Upon success, a string with the contents of the script is returned
    followed by an OK response.
 
        Example:
 
        C: Getscript "myscript"
        S: {54}
        S: #this is my wonderful script
        S: reject "I reject all";
        S:
        S: OK
 
 2.10.  DELETESCRIPT Command
 
    Arguments:  String - script name
 
    This command is used to delete a user's Sieve script.  Servers MUST
    reply with a NO response if the script does not exist.  Such
    responses SHOULD include the NONEXISTENT response code.
 
    The server MUST NOT allow the client to delete an active script, so
    the server MUST reply with a NO response if attempted.  Such a
    response SHOULD contain the ACTIVE response code.  If a client wishes
    to delete an active script, it should use the SETACTIVE command to
    disable the script first.
 
        Example:
 
        C: Deletescript "foo"
        S: Ok
 
        C: Deletescript "baz"
        S: No (ACTIVE) "You may not delete an active script"
 
 
 
 
 
 
 
 
 
 
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 2.11.  RENAMESCRIPT Command
 
    Arguments:  String - Old Script name
                String - New Script name
 
    This command is used to rename a user's Sieve script.  Servers MUST
    reply with a NO response if the old script does not exist (in which
    case the NONEXISTENT response code SHOULD be included), or a script
    with the new name already exists (in which case the ALREADYEXISTS
    response code SHOULD be included).  Renaming the active script is
    allowed; the renamed script remains active.
 
        Example:
 
        C: Renamescript "foo" "bar"
        S: Ok
 
        C: Renamescript "baz" "bar"
        S: No "bar already exists"
 
    If the server doesn't support the RENAMESCRIPT command, the client
    can emulate it by performing the following steps:
 
    1.  List available scripts with LISTSCRIPTS.  If the script with the
        new script name exists, then the client should ask the user
        whether to abort the operation, to replace the script (by issuing
        the DELETESCRIPT <newname> after that), or to choose a different
        name.
 
    2.  Download the old script with GETSCRIPT <oldname>.
 
    3.  Upload the old script with the new name: PUTSCRIPT <newname>.
 
    4.  If the old script was active (as reported by LISTSCRIPTS in step
        1), then make the new script active: SETACTIVE <newname>.
 
    5.  Delete the old script: DELETESCRIPT <oldname>.
 
    Note that these steps don't describe how to handle various other
    error conditions (for example, NO response containing QUOTA response
    code in step 3).  Error handling is left as an exercise for the
    reader.
 
 
 
 
 
 
 
 
 
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 2.12.  CHECKSCRIPT Command
 
    Arguments:  String - Script content
 
    The CHECKSCRIPT command is used by the client to verify Sieve script
    validity without storing the script on the server.
 
    The server MUST check the submitted script for syntactic validity,
    which includes checking that all Sieve extensions mentioned in Sieve
    script "require" statement(s) are supported by the Sieve interpreter.
    (Note that if the Sieve interpreter supports the Sieve "ihave"
    extension [I-HAVE], any unrecognized/unsupported extension mentioned
    in the "ihave" test MUST NOT cause the syntactic validation failure.)
    If the script fails this test, the server MUST reply with a NO
    response.  The message given with a NO response MUST be human
    readable and SHOULD contain a specific error message giving the line
    number of the first error.  Implementors should strive to produce
    helpful error messages similar to those given by programming language
    compilers.  Client implementations should note that this may be a
    multiline literal string with more than one error message separated
    by CRLFs.  The human-readable message is in the language returned in
    the latest LANGUAGE capability (or in "i-default"; see Section 1.7),
    encoded in UTF-8 [UTF-8].
 
        Examples:
 
        C: CheckScript {31+}
        C: #comment
        C: InvalidSieveCommand
        C:
        S: NO "line 2: Syntax error"
 
    A ManageSieve server supporting this command MUST NOT check if the
    script will put the current user over its quota limit.
 
    An OK response MAY contain the WARNINGS response code.  In such a
    case, the human-readable message that follows the OK response SHOULD
    contain a specific warning message (or messages) giving the line
    number(s) in the script that might contain errors not intended by the
    script writer.  The human-readable message is in the language
    returned in the latest LANGUAGE capability (or in "i-default"; see
    Section 1.7), encoded in UTF-8 [UTF-8].  A client seeing such a
    response code SHOULD present the message to the user.
 
 
 
 
 
 
 
 
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 2.13.  NOOP Command
 
    Arguments:  String - tag to echo back (optional)
 
    The NOOP command does nothing, beyond returning a response to the
    client.  It may be used by clients for protocol re-synchronization or
    to reset any inactivity auto-logout timer on the server.
 
    The response to the NOOP command is always OK, followed by the TAG
    response code together with the supplied string.  If no string was
    supplied in the NOOP command, the TAG response code MUST NOT be
    included.
 
        Examples:
 
        C: NOOP
        S: OK "NOOP completed"
 
        C: NOOP "STARTTLS-SYNC-42"
        S: OK (TAG {16}
        S: STARTTLS-SYNC-42) "Done"
 
 2.14.  Recommended Extensions
 
    The UNAUTHENTICATE extension (advertised as the "UNAUTHENTICATE"
    capability with no parameters) defines a new UNAUTHENTICATE command,
    which allows a client to return the server to non-authenticated
    state.  Support for this extension is RECOMMENDED.
 
 2.14.1.  UNAUTHENTICATE Command
 
    The UNAUTHENTICATE command returns the server to the
    non-authenticated state.  It doesn't affect any previously
    established TLS [TLS] or SASL (Section 2.1) security layer.
 
    The UNAUTHENTICATE command is only valid in authenticated state.  If
    issued in a wrong state, the server MUST reject it with a NO
    response.
 
    The UNAUTHENTICATE command has no parameters.
 
    When issued in the authenticated state, the UNAUTHENTICATE command
    MUST NOT fail (i.e., it must never return anything other than OK or
    BYE).
 
 
 
 
 
 
 
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 3.  Sieve URL Scheme
 
    URI scheme name: sieve
 
    Status: permanent
 
    URI scheme syntax: Described using ABNF [ABNF].  Some ABNF
    productions not defined below are from [URI-GEN].
 
          sieveurl = sieveurl-server / sieveurl-list-scripts /
                     sieveurl-script
 
          sieveurl-server = "sieve://" authority
 
          sieveurl-list-scripts = "sieve://" authority ["/"]
 
          sieveurl-script = "sieve://" authority "/"
                            [owner "/"] scriptname
 
          authority = <defined in [URI-GEN]>
 
          owner         = *ochar
                          ;; %-encoded version of [SASL] authorization
                          ;; identity (script owner) or "userid".
                          ;;
                          ;; Empty owner is used to reference
                          ;; global scripts.
                          ;;
                          ;; Note that ASCII characters such as " ", ";",
                          ;; "&", "=", "/" and "?" must be %-encoded
                          ;; as per rule specified in [URI-GEN].
 
          scriptname    = 1*ochar
                          ;; %-encoded version of UTF-8 representation
                          ;; of the script name.
                          ;; Note that ASCII characters such as " ", ";",
                          ;; "&", "=", "/" and "?" must be %-encoded
                          ;; as per rule specified in [URI-GEN].
 
          ochar         = unreserved / pct-encoded / sub-delims-sh /
                          ":" / "@"
                          ;; Same as [URI-GEN] 'pchar',
                          ;; but without ";", "&" and "=".
 
          unreserved = <defined in [URI-GEN]>
 
          pct-encoded = <defined in [URI-GEN]>
 
 
 
 
 Melnikov & Martin            Standards Track                   [Page 29]
 
 RFC 5804                       ManageSieve                     July 2010
 
 
          sub-delims-sh = "!" / "$" / "'" / "(" / ")" /
                          "*" / "+" / ","
                          ;; Same as [URI-GEN] sub-delims,
                          ;; but without ";", "&" and "=".
 
    URI scheme semantics:
 
       A Sieve URL identifies a Sieve server or a Sieve script on a Sieve
       server.  The latter form is associated with the application/sieve
       MIME type defined in [SIEVE].  There is no MIME type associated
       with the former form of Sieve URI.
 
       The server form is used in the REFERRAL response code (see Section
       1.3) in order to designate another server where the client should
       perform its operations.
 
       The script form allows to retrieve (GETSCRIPT), update
       (PUTSCRIPT), delete (DELETESCRIPT), or activate (SETACTIVE) the
       named script; however, the most typical action would be to
       retrieve the script.  If the script name is empty (omitted), the
       URI requests that the client lists available scripts using the
       LISTSCRIPTS command.
 
    Encoding considerations:
 
       The script name and/or the owner, if present, is in UTF-8.  Non--
       US-ASCII UTF-8 octets MUST be percent-encoded as described in
       [URI-GEN].  US-ASCII characters such as " " (space), ";", "&",
       "=", "/" and "?"  MUST be %-encoded as described in [URI-GEN].
       Note that "&" and "?" are in this list in order to allow for
       future extensions.
 
       Note that the empty owner (e.g., sieve://example.com//script) is
       different from the missing owner (e.g.,
       sieve://example.com/script) and is reserved for referencing global
       scripts.
 
       The user name (in the "authority" part), if present, is in UTF-8.
       Non-US-ASCII UTF-8 octets MUST be percent-encoded as described in
       [URI-GEN].
 
    Applications/protocols that use this URI scheme name:
    ManageSieve [RFC5804] clients and servers.  Clients that can store
    user preferences in protocols such as [LDAP] or [ACAP].
 
    Interoperability considerations: None.
 
 
 
 
 
 Melnikov & Martin            Standards Track                   [Page 30]
 
 RFC 5804                       ManageSieve                     July 2010
 
 
    Security considerations:
    The <scriptname> part of a ManageSieve URL might potentially disclose
    some confidential information about the author of the script or,
    depending on a ManageSieve implementation, about configuration of the
    mail system.  The latter might be used to prepare for a more complex
    attack on the mail system.
 
    Clients resolving ManageSieve URLs that wish to achieve data
    confidentiality and/or integrity SHOULD use the STARTTLS command (if
    supported by the server) before starting authentication, or use a
    SASL mechanism, such as GSSAPI, that provides a confidentiality
    security layer.
 
    Contact: Alexey Melnikov <alexey.melnikov@isode.com>
 
    Author/Change controller: IESG.
 
    References: This document and RFC 5228 [SIEVE].
 
 4.  Formal Syntax
 
    The following syntax specification uses the Augmented Backus-Naur
    Form (BNF) notation as specified in [ABNF].  This uses the ABNF core
    rules as specified in Appendix A of the ABNF specification [ABNF].
    "UTF8-2", "UTF8-3", and "UTF8-4" non-terminal are defined in [UTF-8].
 
    Except as noted otherwise, all alphabetic characters are case-
    insensitive.  The use of upper- or lowercase characters to define
    token strings is for editorial clarity only.  Implementations MUST
    accept these strings in a case-insensitive fashion.
 
     SAFE-CHAR             = %x01-09 / %x0B-0C / %x0E-21 / %x23-5B /
                             %x5D-7F
                             ;; any TEXT-CHAR except QUOTED-SPECIALS
 
     QUOTED-CHAR           = SAFE-UTF8-CHAR / "\" QUOTED-SPECIALS
 
     QUOTED-SPECIALS       = DQUOTE / "\"
 
     SAFE-UTF8-CHAR        = SAFE-CHAR / UTF8-2 / UTF8-3 / UTF8-4
                             ;; <UTF8-2>, <UTF8-3>, and <UTF8-4>
                             ;; are defined in [UTF-8].
 
     ATOM-CHAR             = "!" / %x23-27 / %x2A-5B / %x5D-7A / %x7C-7E
                             ;; Any CHAR except ATOM-SPECIALS
 
     ATOM-SPECIALS         = "(" / ")" / "{" / SP / CTL / QUOTED-SPECIALS
 
 
 
 
 Melnikov & Martin            Standards Track                   [Page 31]
 
 RFC 5804                       ManageSieve                     July 2010
 
 
     NZDIGIT               = %x31-39
                             ;; 1-9
 
     atom                  = 1*1024ATOM-CHAR
 
     iana-token            = atom
                             ;; MUST be registered with IANA
 
     auth-type             = DQUOTE auth-type-name DQUOTE
 
     auth-type-name        = iana-token
                             ;; as defined in SASL [SASL]
 
     command               = (command-any / command-auth /
                              command-nonauth) CRLF
                             ;; Modal based on state
 
     command-any           = command-capability / command-logout /
                             command-noop
                             ;; Valid in all states
 
     command-auth          = command-getscript / command-setactive /
                             command-listscripts / command-deletescript /
                             command-putscript / command-checkscript /
                             command-havespace /
                             command-renamescript /
                             command-unauthenticate
                             ;; Valid only in Authenticated state
 
     command-nonauth       = command-authenticate / command-starttls
                             ;; Valid only when in Non-Authenticated
                             ;; state
 
     command-authenticate  = "AUTHENTICATE" SP auth-type [SP string]
                             *(CRLF string)
 
     command-capability    = "CAPABILITY"
 
     command-deletescript  = "DELETESCRIPT" SP sieve-name
 
     command-getscript     = "GETSCRIPT" SP sieve-name
 
     command-havespace     = "HAVESPACE" SP sieve-name SP number
 
     command-listscripts   = "LISTSCRIPTS"
 
     command-noop          = "NOOP" [SP string]
 
 
 
 
 Melnikov & Martin            Standards Track                   [Page 32]
 
 RFC 5804                       ManageSieve                     July 2010
 
 
     command-logout        = "LOGOUT"
 
     command-putscript     = "PUTSCRIPT" SP sieve-name SP sieve-script
 
     command-checkscript   = "CHECKSCRIPT" SP sieve-script
 
     sieve-script          = string
 
     command-renamescript  = "RENAMESCRIPT" SP old-sieve-name SP
                             new-sieve-name
 
     old-sieve-name        = sieve-name
 
     new-sieve-name        = sieve-name
 
     command-setactive     = "SETACTIVE" SP active-sieve-name
 
     command-starttls      = "STARTTLS"
 
     command-unauthenticate= "UNAUTHENTICATE"
 
     extend-token          = atom
                             ;; MUST be defined by a Standards Track or
                             ;; IESG-approved experimental protocol
                             ;; extension
 
     extension-data        = extension-item *(SP extension-item)
 
     extension-item        = extend-token / string / number /
                             "(" [extension-data] ")"
 
     literal-c2s           = "{" number "+}" CRLF *OCTET
                             ;; The number represents the number of
                             ;; octets.
                             ;; This type of literal can only be sent
                             ;; from the client to the server.
 
     literal-s2c           = "{" number "}" CRLF *OCTET
                             ;; Almost identical to literal-c2s,
                             ;; but with no '+' character.
                             ;; The number represents the number of
                             ;; octets.
                             ;; This type of literal can only be sent
                             ;; from the server to the client.
 
 
 
 
 
 
 
 Melnikov & Martin            Standards Track                   [Page 33]
 
 RFC 5804                       ManageSieve                     July 2010
 
 
     number                = (NZDIGIT *DIGIT) / "0"
                             ;; A 32-bit unsigned number
                             ;; with no extra leading zeros.
                             ;; (0 <= n < 4,294,967,296)
 
     number-str            = string
                             ;; <number> encoded as a <string>.
 
     quoted                = DQUOTE *1024QUOTED-CHAR DQUOTE
                             ;; limited to 1024 octets between the <">s
 
     resp-code             = "AUTH-TOO-WEAK" / "ENCRYPT-NEEDED" / "QUOTA"
                             ["/" ("MAXSCRIPTS" / "MAXSIZE")] /
                             resp-code-sasl /
                             resp-code-referral /
                             "TRANSITION-NEEDED" / "TRYLATER" /
                             "ACTIVE" / "NONEXISTENT" /
                             "ALREADYEXISTS" / "WARNINGS" /
                             "TAG" SP string /
                             resp-code-ext
 
     resp-code-referral    = "REFERRAL" SP sieveurl
 
     resp-code-sasl        = "SASL" SP string
 
     resp-code-name        = iana-token
                             ;; The response code name is hierarchical,
                             ;; separated by '/'.
                             ;; The response code name MUST NOT start
                             ;; with '/'.
 
     resp-code-ext         = resp-code-name [SP extension-data]
                             ;; unknown response codes MUST be tolerated
                             ;; by the client.
 
     response              = response-authenticate /
                             response-logout /
                             response-getscript /
                             response-setactive /
                             response-listscripts /
                             response-deletescript /
                             response-putscript /
                             response-checkscript /
                             response-capability /
                             response-havespace /
                             response-starttls /
                             response-renamescript /
                             response-noop /
 
 
 
 Melnikov & Martin            Standards Track                   [Page 34]
 
 RFC 5804                       ManageSieve                     July 2010
 
 
                             response-unauthenticate
 
     response-authenticate = *(string CRLF)
                             ((response-ok [response-capability]) /
                              response-nobye)
                             ;; <response-capability> is REQUIRED if a
                             ;; SASL security layer was negotiated and
                             ;; MUST be omitted otherwise.
 
     response-capability   = *(single-capability) response-oknobye
 
     single-capability     = capability-name [SP string] CRLF
 
     capability-name       = string
 
                             ;; Note that literal-s2c is allowed.
 
     initial-capabilities  = DQUOTE "IMPLEMENTATION" DQUOTE SP string /
                             DQUOTE "SASL" DQUOTE SP sasl-mechs /
                             DQUOTE "SIEVE" DQUOTE SP sieve-extensions /
                             DQUOTE "MAXREDIRECTS" DQUOTE SP number-str /
                             DQUOTE "NOTIFY" DQUOTE SP notify-mechs /
                             DQUOTE "STARTTLS" DQUOTE /
                             DQUOTE "LANGUAGE" DQUOTE SP language /
                             DQUOTE "VERSION" DQUOTE SP version /
                             DQUOTE "OWNER" DQUOTE SP string
                             ;; Each capability conforms to
                             ;; the syntax for single-capability.
                             ;; Also, note that the capability name
                             ;; can be returned as either literal-s2c
                             ;; or quoted, even though only "quoted"
                             ;; string is shown above.
 
     version = ( DQUOTE "1.0" DQUOTE ) / version-ext
 
     version-ext = DQUOTE ver-major "." ver-minor DQUOTE
                  ; Future versions specified in updates
                  ; to this document.  An increment to
                  ; the ver-major means a backward-incompatible
                  ; change to the protocol, e.g., "3.5" (ver-major "3")
                  ; is not backward-compatible with any "2.X" version.
                  ; Any version "Z.W" MUST be backward compatible
                  ; with any version "Z.Q", where Q < W.
                  ; For example, version "2.4" is backward compatible
                  ; with version "2.0", "2.1", "2.2", and "2.3".
 
     ver-major = number
 
 
 
 
 Melnikov & Martin            Standards Track                   [Page 35]
 
 RFC 5804                       ManageSieve                     July 2010
 
 
     ver-minor = number
 
     sasl-mechs = string
                  ; Space-separated list of SASL mechanisms,
                  ; each SASL mechanism name complies with rules
                  ; specified in [SASL].
                  ; Can be empty.
 
     sieve-extensions = string
                  ; Space-separated list of supported SIEVE extensions.
                  ; Can be empty.
 
     language     = string
                  ; Contains <Language-Tag> from [RFC5646].
 
 
     notify-mechs = string
                  ; Space-separated list of URI schema parts
                  ; for supported notification [NOTIFY] methods.
                  ; MUST NOT be empty.
 
     response-deletescript = response-oknobye
 
     response-getscript    = (sieve-script CRLF response-ok) /
                             response-nobye
 
     response-havespace    = response-oknobye
 
     response-listscripts  = *(sieve-name [SP "ACTIVE"] CRLF)
                             response-oknobye
                             ;; ACTIVE may only occur with one sieve-name
 
     response-logout       = response-oknobye
 
     response-unauthenticate= response-oknobye
                              ;; "NO" response can only be returned when
                              ;; the command is issued in a wrong state
                              ;; or has a wrong number of parameters
 
     response-ok           = "OK" [SP "(" resp-code ")"]
                             [SP string] CRLF
                             ;; The string contains human-readable text
                             ;; encoded as UTF-8.
 
     response-nobye        = ("NO" / "BYE") [SP "(" resp-code ")"]
                             [SP string] CRLF
                             ;; The string contains human-readable text
                             ;; encoded as UTF-8.
 
 
 
 Melnikov & Martin            Standards Track                   [Page 36]
 
 RFC 5804                       ManageSieve                     July 2010
 
 
     response-oknobye      = response-ok / response-nobye
 
     response-noop         = response-ok
 
     response-putscript    = response-oknobye
 
     response-checkscript  = response-oknobye
 
     response-renamescript = response-oknobye
 
     response-setactive    = response-oknobye
 
     response-starttls     = (response-ok response-capability) /
                             response-nobye
 
     sieve-name            = string
                             ;; See Section 1.6 for the full list of
                             ;; prohibited characters.
                             ;; Empty string is not allowed.
 
     active-sieve-name     = string
                             ;; See Section 1.6 for the full list of
                             ;; prohibited characters.
                             ;; This is similar to <sieve-name>, but
                             ;; empty string is allowed and has a special
                             ;; meaning.
 
     string                = quoted / literal-c2s / literal-s2c
                             ;; literal-c2s is only allowed when sent
                             ;; from the client to the server.
                             ;; literal-s2c is only allowed when sent
                             ;; from the server to the client.
                             ;; quoted is allowed in either direction.
 
 5.  Security Considerations
 
    The AUTHENTICATE command uses SASL [SASL] to provide authentication
    and authorization services.  Integrity and privacy services can be
    provided by [SASL] and/or [TLS].  When a SASL mechanism is used, the
    security considerations for that mechanism apply.
 
    This protocol's transactions are susceptible to passive observers or
    man-in-the-middle attacks that alter the data, unless the optional
    encryption and integrity services of the SASL (via the AUTHENTICATE
    command) and/or [TLS] (via the STARTTLS command) are enabled, or an
    external security mechanism is used for protection.  It may be useful
    to allow configuration of both clients and servers to refuse to
    transfer sensitive information in the absence of strong encryption.
 
 
 
 Melnikov & Martin            Standards Track                   [Page 37]
 
 RFC 5804                       ManageSieve                     July 2010
 
 
    If an implementation supports SASL mechanisms that are vulnerable to
    passive eavesdropping attacks (such as [PLAIN]), then the
    implementation MUST support at least one configuration where these
    SASL mechanisms are not advertised or used without the presence of an
    external security layer such as [TLS].
 
    Some response codes returned on failed AUTHENTICATE command may
    disclose whether or not the username is valid (e.g., TRANSITION-
    NEEDED), so server implementations SHOULD provide the ability to
    disable these features (or make them not conditional on a per-user
    basis) for sites concerned about such disclosure.  In the case of
    ENCRYPT-NEEDED, if it is applied to all identities then no extra
    information is disclosed, but if it is applied on a per-user basis it
    can disclose information.
 
    A compromised or malicious server can use the TRANSITION-NEEDED
    response code to force the client that is configured to use a
    mechanism that does not disclose the user's password to the server
    (e.g., Kerberos), to send the bare password to the server.  Clients
    SHOULD have the ability to disable the password transition feature,
    or disclose that risk to the user and offer the user an option of how
    to proceed.
 
 6.  IANA Considerations
 
    IANA has reserved TCP port number 4190 for use with the ManageSieve
    protocol described in this document.
 
    IANA has registered the "sieve" URI scheme defined in Section 3 of
    this document.
 
    IANA has registered "sieve" in the "GSSAPI/Kerberos/SASL Service
    Names" registry.
 
    IANA has created a new registry for ManageSieve capabilities.  The
    registration template for ManageSieve capabilities is specified in
    Section 6.1.  ManageSieve protocol capabilities MUST be specified in
    a Standards-Track or IESG-approved Experimental RFC.
 
    IANA has created a new registry for ManageSieve response codes.  The
    registration template for ManageSieve response codes is specified in
    Section 6.3.  ManageSieve protocol response codes MUST be specified
    in a Standards-Track or IESG-approved Experimental RFC.
 
 
 
 
 
 
 
 
 Melnikov & Martin            Standards Track                   [Page 38]
 
 RFC 5804                       ManageSieve                     July 2010
 
 
 6.1.  ManageSieve Capability Registration Template
 
    To: iana@iana.org
    Subject: ManageSieve Capability Registration
 
    Please register the following ManageSieve capability:
 
    Capability name:
    Description:
    Relevant publications:
    Person & email address to contact for further information:
    Author/Change controller:
 
 6.2.  Registration of Initial ManageSieve Capabilities
 
    To: iana@iana.org
    Subject: ManageSieve Capability Registration
 
    Please register the following ManageSieve capabilities:
 
    Capability name:  IMPLEMENTATION
    Description:   Its value contains the name of the server
                   implementation and its version.
    Relevant publications:  this RFC, Section 1.7.
    Person & email address to contact for further information:
                   Alexey Melnikov <alexey.melnikov@isode.com>
    Author/Change controller:  IESG.
 
    Capability name:  SASL
    Description:   Its value contains a space-separated list of SASL
                   mechanisms supported by the server.
    Relevant publications:  this RFC, Sections 1.7 and 2.1.
    Person & email address to contact for further information:
                   Alexey Melnikov <alexey.melnikov@isode.com>
    Author/Change controller:  IESG.
 
    Capability name:  SIEVE
    Description:   Its value contains a space-separated list of supported
                   SIEVE extensions.
    Relevant publications:  this RFC, Section 1.7.  Also [SIEVE].
    Person & email address to contact for further information:
                   Alexey Melnikov <alexey.melnikov@isode.com>
    Author/Change controller:  IESG.
 
 
 
 
 
 
 
 
 Melnikov & Martin            Standards Track                   [Page 39]
 
 RFC 5804                       ManageSieve                     July 2010
 
 
    Capability name:  STARTTLS
    Description:   This capability is returned if the server supports TLS
                   (STARTTLS command).
    Relevant publications:  this RFC, Sections 1.7 and 2.2.
    Person & email address to contact for further information:
                   Alexey Melnikov <alexey.melnikov@isode.com>
    Author/Change controller:  IESG.
 
    Capability name:  NOTIFY
    Description:   This capability is returned if the server supports the
                   'enotify' [NOTIFY] Sieve extension.
    Relevant publications:  this RFC, Section 1.7.
    Person & email address to contact for further information:
                   Alexey Melnikov <alexey.melnikov@isode.com>
    Author/Change controller:  IESG.
 
    Capability name:  MAXREDIRECTS
    Description:   This capability returns the limit on the number of
                   Sieve "redirect" actions a script can perform during a
                   single evaluation.  The value is a non-negative number
                   represented as a ManageSieve string.
    Relevant publications:  this RFC, Section 1.7.
    Person & email address to contact for further information:
                   Alexey Melnikov <alexey.melnikov@isode.com>
    Author/Change controller:  IESG.
 
    Capability name:  LANGUAGE
    Description:   The language (<Language-Tag> from [RFC5646]) currently
                   used for human-readable error messages.
    Relevant publications:  this RFC, Section 1.7.
    Person & email address to contact for further information:
                   Alexey Melnikov <alexey.melnikov@isode.com>
    Author/Change controller:  IESG.
 
    Capability name:  OWNER
    Description:   Its value contains the UTF-8-encoded name of the
                   currently logged-in user ("authorization identity"
                   according to RFC 4422).
    Relevant publications:  this RFC, Section 1.7.
    Person & email address to contact for further information:
                   Alexey Melnikov <alexey.melnikov@isode.com>
    Author/Change controller:  IESG.
 
 
 
 
 
 
 
 
 
 Melnikov & Martin            Standards Track                   [Page 40]
 
 RFC 5804                       ManageSieve                     July 2010
 
 
    Capability name:  VERSION
    Description:   This capability is returned if the server is compliant
                   with RFC 5804; i.e., that it supports RENAMESCRIPT,
                   CHECKSCRIPT, and NOOP commands.
    Relevant publications:  this RFC, Sections 2.11, 2.12, and 2.13.
    Person & email address to contact for further information:
                   Alexey Melnikov <alexey.melnikov@isode.com>
    Author/Change controller:  IESG.
 
 6.3.  ManageSieve Response Code Registration Template
 
    To: iana@iana.org
    Subject: ManageSieve Response Code Registration
 
    Please register the following ManageSieve response code:
 
       Response Code:
       Arguments (use ABNF to specify syntax, or the word NONE if none
       can be specified):
       Purpose:
       Published Specification(s):
       Person & email address to contact for further information:
       Author/Change controller:
 
 6.4.  Registration of Initial ManageSieve Response Codes
 
    To: iana@iana.org
    Subject: ManageSieve Response Code Registration
 
    Please register the following ManageSieve response codes:
 
    Response Code: AUTH-TOO-WEAK
    Arguments (use ABNF to specify syntax, or the word NONE if none can
    be specified):  NONE
    Purpose:       This response code is returned in the NO response from
                   an AUTHENTICATE command.  It indicates that site
                   security policy forbids the use of the requested
                   mechanism for the specified authentication identity.
    Published Specification(s):  [RFC5804]
    Person & email address to contact for further information:
                   Alexey Melnikov <alexey.melnikov@isode.com>
    Author/Change controller:  IESG.
 
 
 
 
 
 
 
 
 
 Melnikov & Martin            Standards Track                   [Page 41]
 
 RFC 5804                       ManageSieve                     July 2010
 
 
    Response Code: ENCRYPT-NEEDED
    Arguments (use ABNF to specify syntax, or the word NONE if none can
    be specified):  NONE
    Purpose:       This response code is returned in the NO response from
                   an AUTHENTICATE command.  It indicates that site
                   security policy requires the use of a strong
                   encryption mechanism for the specified authentication
                   identity and mechanism.
    Published Specification(s):  [RFC5804]
    Person & email address to contact for further information:
                   Alexey Melnikov <alexey.melnikov@isode.com>
    Author/Change controller:  IESG.
 
    Response Code: QUOTA
    Arguments (use ABNF to specify syntax, or the word NONE if none can
    be specified):  NONE
    Purpose:       If this response code is returned in the NO/BYE
                   response, it means that the command would have placed
                   the user above the site-defined quota constraints.  If
                   this response code is returned in the OK response, it
                   can mean that the user is near its quota or that the
                   user exceeded its quota, but the server supports soft
                   quotas.
    Published Specification(s):  [RFC5804]
    Person & email address to contact for further information:
                   Alexey Melnikov <alexey.melnikov@isode.com>
    Author/Change controller:  IESG.
 
    Response Code: QUOTA/MAXSCRIPTS
    Arguments (use ABNF to specify syntax, or the word NONE if none can
    be specified):  NONE
    Purpose:       If this response code is returned in the NO/BYE
                   response, it means that the command would have placed
                   the user above the site-defined limit on the number of
                   Sieve scripts.  If this response code is returned in
                   the OK response, it can mean that the user is near its
                   quota or that the user exceeded its quota, but the
                   server supports soft quotas.  This response code is a
                   more specific version of the QUOTA response code.
    Published Specification(s):  [RFC5804]
    Person & email address to contact for further information:
                   Alexey Melnikov <alexey.melnikov@isode.com>
    Author/Change controller:  IESG.
 
 
 
 
 
 
 
 
 Melnikov & Martin            Standards Track                   [Page 42]
 
 RFC 5804                       ManageSieve                     July 2010
 
 
    Response Code: QUOTA/MAXSIZE
    Arguments (use ABNF to specify syntax, or the word NONE if none can
    be specified):  NONE
    Purpose:       If this response code is returned in the NO/BYE
                   response, it means that the command would have placed
                   the user above the site-defined maximum script size.
                   If this response code is returned in the OK response,
                   it can mean that the user is near its quota or that
                   the user exceeded its quota, but the server supports
                   soft quotas.  This response code is a more specific
                   version of the QUOTA response code.
    Published Specification(s):  [RFC5804]
    Person & email address to contact for further information:
                   Alexey Melnikov <alexey.melnikov@isode.com>
    Author/Change controller:  IESG.
 
    Response Code: REFERRAL
    Arguments (use ABNF to specify syntax, or the word NONE if none can
    be specified):  <sieveurl>
    Purpose:       This response code may be returned with a BYE result
                   from any command, and includes a mandatory parameter
                   that indicates what server to access to manage this
                   user's Sieve scripts.  The server will be specified by
                   a Sieve URL (see Section 3).  The scriptname portion
                   of the URL MUST NOT be specified.  The client should
                   authenticate to the specified server and use it for
                   all further commands in the current session.
    Published Specification(s):  [RFC5804]
    Person & email address to contact for further information:
                   Alexey Melnikov <alexey.melnikov@isode.com>
    Author/Change controller:  IESG.
 
    Response Code: SASL
    Arguments (use ABNF to specify syntax, or the word NONE if none can
    be specified):  <string>
    Purpose:       This response code can occur in the OK response to a
                   successful AUTHENTICATE command and includes the
                   optional final server response data from the server as
                   specified by [SASL].
    Published Specification(s):  [RFC5804]
    Person & email address to contact for further information:
                   Alexey Melnikov <alexey.melnikov@isode.com>
    Author/Change controller:  IESG.
 
 
 
 
 
 
 
 
 Melnikov & Martin            Standards Track                   [Page 43]
 
 RFC 5804                       ManageSieve                     July 2010
 
 
    Response Code: TRANSITION-NEEDED
    Arguments (use ABNF to specify syntax, or the word NONE if none can
    be specified):  NONE
    Purpose:       This response code occurs in a NO response of an
                   AUTHENTICATE command.  It indicates that the user name
                   is valid, but the entry in the authentication database
                   needs to be updated in order to permit authentication
                   with the specified mechanism.  This is typically done
                   by establishing a secure channel using TLS, followed
                   by authenticating once using the [PLAIN]
                   authentication mechanism.  The selected mechanism
                   SHOULD then work for authentications in subsequent
                   sessions.
    Published Specification(s):  [RFC5804]
    Person & email address to contact for further information:
                   Alexey Melnikov <alexey.melnikov@isode.com>
    Author/Change controller:  IESG.
 
    Response Code: TRYLATER
    Arguments (use ABNF to specify syntax, or the word NONE if none can
    be specified):  NONE
    Purpose:       A command failed due to a temporary server failure.
                   The client MAY continue using local information and
                   try the command later.  This response code only make
                   sense when returned in a NO/BYE response.
    Published Specification(s):  [RFC5804]
    Person & email address to contact for further information:
                   Alexey Melnikov <alexey.melnikov@isode.com>
    Author/Change controller:  IESG.
 
    Response Code: ACTIVE
    Arguments (use ABNF to specify syntax, or the word NONE if none can
    be specified):  NONE
    Purpose:       A command failed because it is not allowed on the
                   active script, for example, DELETESCRIPT on the active
                   script.  This response code only makes sense when
                   returned in a NO/BYE response.
    Published Specification(s):  [RFC5804]
    Person & email address to contact for further information:
                   Alexey Melnikov <alexey.melnikov@isode.com>
    Author/Change controller:  IESG.
 
 
 
 
 
 
 
 
 
 
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    Response Code: NONEXISTENT
    Arguments (use ABNF to specify syntax, or the word NONE if none can
    be specified):  NONE
    Purpose:       A command failed because the referenced script name
                   doesn't exist.  This response code only makes sense
                   when returned in a NO/BYE response.
    Published Specification(s):  [RFC5804]
    Person & email address to contact for further information:
                   Alexey Melnikov <alexey.melnikov@isode.com>
    Author/Change controller:  IESG.
 
    Response Code: ALREADYEXISTS
    Arguments (use ABNF to specify syntax, or the word NONE if none can
    be specified):  NONE
    Purpose:       A command failed because the referenced script name
                   already exists.  This response code only makes sense
                   when returned in a NO/BYE response.
    Published Specification(s):  [RFC5804]
    Person & email address to contact for further information:
                   Alexey Melnikov <alexey.melnikov@isode.com>
    Author/Change controller:  IESG.
 
    Response Code: WARNINGS
    Arguments (use ABNF to specify syntax, or the word NONE if none can
    be specified):  NONE
    Purpose:       This response code MAY be returned by the server in
                   the OK response (but it might be returned with the NO/
                   BYE response as well) and signals the client that even
                   though the script is syntactically valid, it might
                   contain errors not intended by the script writer.
    Published Specification(s):  [RFC5804]
    Person & email address to contact for further information:
                   Alexey Melnikov <alexey.melnikov@isode.com>
    Author/Change controller:  IESG.
 
    Response Code: TAG
    Arguments (use ABNF to specify syntax, or the word NONE if none can
    be specified):  string
    Purpose:       This response code name is followed by a string
                   specified in the command that caused this response.
                   It is typically used for client state synchronization.
    Published Specification(s):  [RFC5804]
    Person & email address to contact for further information:
                   Alexey Melnikov <alexey.melnikov@isode.com>
    Author/Change controller:  IESG.
 
 
 
 
 
 
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 7.  Internationalization Considerations
 
    The LANGUAGE capability (see Section 1.7) allows a client to discover
    the current language used in all human-readable responses that might
    be returned at the end of any OK/NO/BYE response.  Human-readable
    text in OK responses typically doesn't need to be shown to the user,
    unless it is returned in response to a PUTSCRIPT or CHECKSCRIPT
    command that also contains the WARNINGS response code (Section 1.3).
    Human-readable text from NO/BYE responses is intended be shown to the
    user, unless the client can automatically handle failure of the
    command that caused such a response.  Clients SHOULD use response
    codes (Section 1.3) for automatic error handling.  Response codes MAY
    also be used by the client to present error messages in a language
    understood by the user, for example, if the LANGUAGE capability
    doesn't return a language understood by the user.
 
    Note that the human-readable text from OK (WARNINGS) or NO/BYE
    responses for PUTSCRIPT/CHECKSCRIPT commands is intended for advanced
    users that understand Sieve language.  Such advanced users are often
    sophisticated enough to be able to handle whatever language the
    server is using, even if it is not their preferred language, and will
    want to see error/warning text no matter what language the server
    puts it in.
 
    A client that generates Sieve script automatically, for example, if
    the script is generated without user intervention or from a UI that
    presents an abstract list of conditions and corresponding actions,
    SHOULD NOT present warning/error messages to the user, because the
    user might not even be aware that the client is using Sieve
    underneath.  However, if the client has a debugging mode, such
    warnings/errors SHOULD be available in the debugging mode.
 
    Note that this document doesn't provide a way to modify the currently
    used language.  It is expected that a future extension will address
    that.
 
 8.  Acknowledgements
 
    Thanks to Simon Josefsson, Larry Greenfield, Allen Johnson, Chris
    Newman, Lyndon Nerenberg, Tim Showalter, Sarah Robeson, Walter Wong,
    Barry Leiba, Arnt Gulbrandsen, Stephan Bosch, Ken Murchison, Phil
    Pennock, Ned Freed, Jeffrey Hutzelman, Mark E. Mallett, Dilyan
    Palauzov, Dave Cridland, Aaron Stone, Robert Burrell Donkin, Patrick
    Ben Koetter, Bjoern Hoehrmann, Martin Duerst, Pasi Eronen, Magnus
    Westerlund, Tim Polk, and Julien Coloos for help with this document.
    Special thank you to Phil Pennock for providing text for the NOOP
    command, as well as finding various bugs in the document.
 
 
 
 
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 9.  References
 
 9.1.  Normative References
 
    [ABNF]         Crocker, D. and P. Overell, "Augmented BNF for Syntax
                   Specifications: ABNF", STD 68, RFC 5234, January 2008.
 
    [ACAP]         Newman, C. and J. Myers, "ACAP -- Application
                   Configuration Access Protocol", RFC 2244, November
                   1997.
 
    [BASE64]       Josefsson, S., "The Base16, Base32, and Base64 Data
                   Encodings", RFC 4648, October 2006.
 
    [DNS-SRV]      Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR
                   for specifying the location of services (DNS SRV)",
                   RFC 2782, February 2000.
 
    [KEYWORDS]     Bradner, S., "Key words for use in RFCs to Indicate
                   Requirement Levels", BCP 14, RFC 2119, March 1997.
 
    [NET-UNICODE]  Klensin, J. and M. Padlipsky, "Unicode Format for
                   Network Interchange", RFC 5198, March 2008.
 
    [NOTIFY]       Melnikov, A., Leiba, B., Segmuller, W., and T. Martin,
                   "Sieve Email Filtering: Extension for Notifications",
                   RFC 5435, January 2009.
 
    [RFC2277]      Alvestrand, H., "IETF Policy on Character Sets and
                   Languages", BCP 18, RFC 2277, January 1998.
 
    [RFC2460]      Deering, S. and R. Hinden, "Internet Protocol, Version
                   6 (IPv6) Specification", RFC 2460, December 1998.
 
    [RFC3490]      Faltstrom, P., Hoffman, P., and A. Costello,
                   "Internationalizing Domain Names in Applications
                   (IDNA)", RFC 3490, March 2003.
 
    [RFC4519]      Sciberras, A., "Lightweight Directory Access Protocol
                   (LDAP): Schema for User Applications", RFC 4519, June
                   2006.
 
    [RFC5646]      Phillips, A. and M. Davis, "Tags for Identifying
                   Languages", BCP 47, RFC 5646, September 2009.
 
    [RFC791]       Postel, J., "Internet Protocol", STD 5, RFC 791,
                   September 1981.
 
 
 
 
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    [SASL]         Melnikov, A. and K. Zeilenga, "Simple Authentication
                   and Security Layer (SASL)", RFC 4422, June 2006.
 
    [SASLprep]     Zeilenga, K., "SASLprep: Stringprep Profile for User
                   Names and Passwords", RFC 4013, February 2005.
 
    [SCRAM]        Menon-Sen, A., Melnikov, A., Newman, C., and N.
                   Williams, "Salted Challenge Response Authentication
                   Mechanism (SCRAM) SASL and GSS-API Mechanisms", RFC
                   5802, July 2010.
 
    [SIEVE]        Guenther, P. and T. Showalter, "Sieve: An Email
                   Filtering Language", RFC 5228, January 2008.
 
    [StringPrep]   Hoffman, P. and M. Blanchet, "Preparation of
                   Internationalized Strings ("stringprep")", RFC 3454,
                   December 2002.
 
    [TLS]          Dierks, T. and E. Rescorla, "The Transport Layer
                   Security (TLS) Protocol Version 1.2", RFC 5246, August
                   2008.
 
    [URI-GEN]      Berners-Lee, T., Fielding, R., and L. Masinter,
                   "Uniform Resource Identifier (URI): Generic Syntax",
                   STD 66, RFC 3986, January 2005.
 
    [UTF-8]        Yergeau, F., "UTF-8, a transformation format of ISO
                   10646", STD 63, RFC 3629, November 2003.
 
    [X509]         Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
                   Housley, R., and W. Polk, "Internet X.509 Public Key
                   Infrastructure Certificate and Certificate Revocation
                   List (CRL) Profile", RFC 5280, May 2008.
 
    [X509-SRV]     Santesson, S., "Internet X.509 Public Key
                   Infrastructure Subject Alternative Name for Expression
                   of Service Name", RFC 4985, August 2007.
 
 9.2.  Informative References
 
    [DIGEST-MD5]   Leach, P. and C. Newman, "Using Digest Authentication
                   as a SASL Mechanism", RFC 2831, May 2000.
 
    [GSSAPI]       Melnikov, A., "The Kerberos V5 ("GSSAPI") Simple
                   Authentication and Security Layer (SASL) Mechanism",
                   RFC 4752, November 2006.
 
 
 
 
 
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 RFC 5804                       ManageSieve                     July 2010
 
 
    [I-HAVE]       Freed, N., "Sieve Email Filtering: Ihave Extension",
                   RFC 5463, March 2009.
 
    [IMAP]         Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL -
                   VERSION 4rev1", RFC 3501, March 2003.
 
    [LDAP]         Zeilenga, K., "Lightweight Directory Access Protocol
                   (LDAP): Technical Specification Road Map", RFC 4510,
                   June 2006.
 
    [PLAIN]        Zeilenga, K., "The PLAIN Simple Authentication and
                   Security Layer (SASL) Mechanism", RFC 4616, August
                   2006.
 
 Authors' Addresses
 
    Alexey Melnikov (editor)
    Isode Limited
    5 Castle Business Village
    36 Station Road
    Hampton, Middlesex  TW12 2BX
    UK
 
    EMail: Alexey.Melnikov@isode.com
 
 
    Tim Martin
    BeThereBeSquare, Inc.
    672 Haight st.
    San Francisco, CA  94117
    USA
 
    Phone: +1 510 260-4175
    EMail: timmartin@alumni.cmu.edu
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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