Simple Mail Transfer Protocol (SMTP) Enhanced Status Codes Registry

(last updated 2008-09-05)

Registries included below:
- Class Sub-Codes
- Subject Sub-Codes
- Enumerated Status Codes


Registry Name: Class Sub-Codes
Reference: [RFC5248]
Registration Procedures: Specification Required

Registry:
Code:               2.XXX.YYY
Summary:            Success
Description:        Success specifies that the DSN is reporting a
                    positive delivery action.  Detail sub-codes may
                    provide notification of transformations required for
                    delivery.
Reference:          [RFC3463] (Standards track)
Submitter:          G. Vaudreuil
Change Controller:  IESG

Code:               4.XXX.YYY
Summary:            Persistent Transient Failure
Description:        A persistent transient failure is one in which the
                    message as sent is valid, but persistence of some
                    temporary condition has caused abandonment or delay of
                    attempts to send the message. If this code accompanies
                    a delivery failure report, sending in the future may be
                    successful.
Reference:          [RFC3463] (Standards track)
Submitter:          G. Vaudreuil
Change Controller:  IESG

Code:               5.XXX.YYY
Summary:            Permanent Failure
Description:        A permanent failure is one which is not likely to be
                    resolved by resending the message in the current form.
                    Some change to the message or the destination must be
                    made for successful delivery.
Reference:          [RFC3463] (Standards track)
Submitter:          G. Vaudreuil
Change Controller:  IESG


Registry Name: Subject Sub-Codes
Reference: [RFC5248]
Registration Procedures: Specification Required

Registry:
Code:               X.0.YYY
Summary:            Other or Undefined Status
Description:        There is no additional subject information available.
Reference:          [RFC3463] (Standards track)
Submitter:          G. Vaudreuil
Change Controller:  IESG

Code:               X.1.YYY
Summary:            Addressing Status
Description:        The address status reports on the originator or
                    destination address.  It may include address syntax or
                    validity.  These errors can generally be corrected by
                    the sender and retried.
Reference:          [RFC3463] (Standards track)
Submitter:          G. Vaudreuil
Change Controller:  IESG

Code:               X.2.YYY
Summary:            Mailbox Status
Description:        Mailbox status indicates that something having to do
                    with the mailbox has caused this DSN.  Mailbox issues are
                    assumed to be under the general control of the recipient.
Reference:          [RFC3463] (Standards track)
Submitter:          G. Vaudreuil
Change Controller:  IESG

Code:               X.3.YYY
Summary:            Mail System Status
Description:        Mail system status indicates that something having to do
                    with the destination system has caused this DSN.  System
                    issues are assumed to be under the general control of the
                    destination system administrator.
Reference:          [RFC3463] (Standards track)
Submitter:          G. Vaudreuil
Change Controller:  IESG

Code:               X.4.YYY
Summary:            Network and Routing Status
Description:        The networking or routing codes report status about the
                    delivery system itself.  These system components include
                    any necessary infrastructure such as directory and routing
                    services.  Network issues are assumed to be under the
                    control of the destination or intermediate system
                    administrator.
Reference:          [RFC3463] (Standards track)
Submitter:          G. Vaudreuil
Change Controller:  IESG

Code:               X.5.YYY
Summary:            Mail Delivery Protocol Status
Description:        The mail delivery protocol status codes report failures
                    involving the message delivery protocol.  These failures
                    include the full range of problems resulting from
                    implementation errors or an unreliable connection.
Reference:          [RFC3463] (Standards track)
Submitter:          G. Vaudreuil
Change Controller:  IESG

Code:               X.6.YYY
Summary:            Message Content or Media Status
Description:        The message content or media status codes report failures
                    involving the content of the message.  These codes report
                    failures due to translation, transcoding, or otherwise
                    unsupported message media.  Message content or media
                    issues are under the control of both the sender and the
                    receiver, both of which must support a common set of
                    supported content-types.
Reference:          [RFC3463] (Standards track)
Submitter:          G. Vaudreuil
Change Controller:  IESG

Code:               X.7.YYY
Summary:            Security or Policy Status
Description:        The security or policy status codes report failures
                    involving policies such as per-recipient or per-host
                    filtering and cryptographic operations.  Security and
                    policy status issues are assumed to be under the control
                    of either or both the sender and recipient.  Both the
                    sender and recipient must permit the exchange of messages
                    and arrange the exchange of necessary keys and
                    certificates for cryptographic operations.
Reference:          [RFC3463] (Standards track)
Submitter:          G. Vaudreuil
Change Controller:  IESG


Registry Name: Enumerated Status Codes
Reference: [RFC5248]
Registration Procedures: Specification Required

Registry:
Code:               X.0.0
Sample Text:        Other undefined Status
Associated basic status code:  Any
Description:        Other undefined status is the only undefined error code.
                    It should be used for all errors for which only the class
                    of the error is known.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.1.0
Sample Text:        Other address status
Associated basic status code:  Not given
Description:        Something about the address specified in the message
                    caused this DSN.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.1.1
Sample Text:        Bad destination mailbox address
Associated basic status code:  451, 550
Description:        The mailbox specified in the address does not exist.
                    For Internet mail names, this means the address portion to
                    the left of the "@" sign is invalid.  This code is only
                    useful for permanent failures.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.1.2
Sample Text:        Bad destination system address
Associated basic status code:  Not given
Description:        The destination system specified in the address does not
                    exist or is incapable of accepting mail.  For Internet mail
                    names, this means the address portion to the right of the "@"
                    is invalid for mail.  This code is only useful for permanent
                    failures.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.1.3
Sample Text:        Bad destination mailbox address syntax
Associated basic status code:  501
Description:        The destination address was syntactically invalid.  This can
                    apply to any field in the address.  This code is only useful
                    for permanent failures.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.1.4
Sample Text:        Destination mailbox address ambiguous
Associated basic status code:  Not given
Description:        The mailbox address as specified matches one or more
                    recipients on the destination system.  This may result if a
                    heuristic address mapping algorithm is used to map the
                    specified address to a local mailbox name.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.1.5
Sample Text:        Destination address valid
Associated basic status code:  250
Description:        This mailbox address as specified was valid.  This status code
                    should be used for positive delivery reports.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.1.6
Sample Text:        Destination mailbox has moved, No forwarding address
Associated basic status code:  Not given
Description:        The mailbox address provided was at one time valid, but mail is
                    no longer being accepted for that address.  This code is only
                    useful for permanent failures.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.1.7
Sample Text:        Bad sender's mailbox address syntax
Associated basic status code:  Not given
Description:        The sender's address was syntactically invalid.  This can apply
                    to any field in the address.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.1.8
Sample Text:        Bad sender's system address
Associated basic status code:  451, 501
Description:        The sender's system specified in the address does not exist or
                    is incapable of accepting return mail.  For domain names, this
                    means the address portion to the right of the "@" is invalid
                    for mail.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.1.9
Sample Text:        Message relayed to non-compliant mailer
Associated basic status code:  Not given
Description:        The mailbox address specified was valid, but the message has
                    been relayed to a system that does not speak this protocol; no
                    further information can be provided.
Reference:          [RFC3886] (Standards Track)
Submitter:          E. Allman
Change controller:  IESG

Code:               X.2.0
Sample Text:        Other or undefined mailbox status
Associated basic status code:  Not given
Description:        The mailbox exists, but something about the destination mailbox
                    has caused the sending of this DSN.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.2.1
Sample Text:        Mailbox disabled, not accepting messages
Associated basic status code:  Not given
Description:        The mailbox exists, but is not accepting messages.  This may be
                    a permanent error if the mailbox will never be re-enabled or a
                    transient error if the mailbox is only temporarily disabled.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.2.2
Sample Text:        Mailbox full
Associated basic status code:  552
Description:        The mailbox is full because the user has exceeded a per-mailbox
                    administrative quota or physical capacity.  The general
                    semantics implies that the recipient can delete messages to
                    make more space available.  This code should be used as a
                    persistent transient failure.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.2.3
Sample Text:        Message length exceeds administrative limit
Associated basic status code:  552
Description:        A per-mailbox administrative message length limit has been
                    exceeded.  This status code should be used when the per-mailbox
                    message length limit is less than the general system limit.
                    This code should be used as a permanent failure.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.2.4
Sample Text:        Mailing list expansion problem
Associated basic status code:  450, 452
Description:        The mailbox is a mailing list address and the mailing list was
                    unable to be expanded.  This code may represent a permanent
                    failure or a persistent transient failure.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.3.0
Sample Text:        Other or undefined mail system status
Associated basic status code:  221, 250, 421, 451, 550, 554
Description:        The destination system exists and normally accepts mail, but
                    something about the system has caused the generation of this
                    DSN.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.3.1
Sample Text:        Mail system full
Associated basic status code:  452
Description:        Mail system storage has been exceeded.  The general semantics
                    imply that the individual recipient may not be able to delete
                    material to make room for additional messages.  This is useful
                    only as a persistent transient error.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.3.2
Sample Text:        System not accepting network messages
Associated basic status code:  453
Description:        The host on which the mailbox is resident is not accepting
                    messages.  Examples of such conditions include an immanent
                    shutdown, excessive load, or system maintenance.  This is
                    useful for both permanent and persistent transient errors.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.3.3
Sample Text:        System not capable of selected features
Associated basic status code:  Not given
Description:        Selected features specified for the message are not supported
                    by the destination system.  This can occur in gateways when
                    features from one domain cannot be mapped onto the supported
                    feature in another.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.3.4
Sample Text:        Message too big for system
Associated basic status code:  552, 554
Description:        The message is larger than per-message size limit.  This limit
                    may either be for physical or administrative reasons.  This is
                    useful only as a permanent error.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.3.5
Sample Text:        System incorrectly configured
Associated basic status code:  Not given
Description:        The system is not configured in a manner that will permit it to
                    accept this message.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.4.0
Sample Text:        Other or undefined network or routing status
Associated basic status code:  Not given
Description:        Something went wrong with the networking, but it is not clear
                    what the problem is, or the problem cannot be well expressed
                    with any of the other provided detail codes.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.4.1
Sample Text:        No answer from host
Associated basic status code:  451
Description:        The outbound connection attempt was not answered, because
                    either the remote system was busy, or was unable to take a
                    call.  This is useful only as a persistent transient error.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.4.2
Sample Text:        Bad connection
Associated basic status code:  421
Description:        The outbound connection was established, but was unable to
                    complete the message transaction, either because of time-out,
                    or inadequate connection quality.  This is useful only as a
                    persistent transient error.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.4.3
Sample Text:        Directory server failure
Associated basic status code:  451, 550
Description:        The network system was unable to forward the message, because a
                    directory server was unavailable.  This is useful only as a
                    persistent transient error.
                    The inability to connect to an Internet DNS server is one
                    example of the directory server failure error.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.4.4
Sample Text:        Unable to route
Associated basic status code:  Not given
Description:        The mail system was unable to determine the next hop for the
                    message because the necessary routing information was
                    unavailable from the directory server.  This is useful for both
                    permanent and persistent transient errors.
                    A DNS lookup returning only an SOA (Start of Administration)
                    record for a domain name is one example of the unable to route
                    error.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.4.5
Sample Text:        Mail system congestion
Associated basic status code:  451
Description:        The mail system was unable to deliver the message because the
                    mail system was congested.  This is useful only as a persistent
                    transient error.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.4.6
Sample Text:        Routing loop detected
Associated basic status code:  Not given
Description:        A routing loop caused the message to be forwarded too many
                    times, either because of incorrect routing tables or a user-
                    forwarding loop.  This is useful only as a persistent transient
                    error.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.4.7
Sample Text:        Delivery time expired
Associated basic status code:  Not given
Description:        The message was considered too old by the rejecting system,
                    either because it remained on that host too long or because the
                    time-to-live value specified by the sender of the message was
                    exceeded.  If possible, the code for the actual problem found
                    when delivery was attempted should be returned rather than this
                    code.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.5.0
Sample Text:        Other or undefined protocol status
Associated basic status code:  220, 250, 251, 252, 253, 451, 452, 454, 458, 459, 501,
                               502, 503, 554
Description:        Something was wrong with the protocol necessary to deliver the
                    message to the next hop and the problem cannot be well
                    expressed with any of the other provided detail codes.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.5.1
Sample Text:        Invalid command
Associated basic status code:  430, 500, 501, 503, 530, 550, 554, 555
Description:        A mail transaction protocol command was issued which was either
                    out of sequence or unsupported.  This is useful only as a
                    permanent error.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.5.2
Sample Text:        Syntax error
Associated basic status code:  500, 501, 502, 550, 555
Description:        A mail transaction protocol command was issued which could not
                    be interpreted, either because the syntax was wrong or the
                    command is unrecognized.  This is useful only as a permanent
                    error.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.5.3
Sample Text:        Too many recipients
Associated basic status code:  451
Description:        More recipients were specified for the message than could have
                    been delivered by the protocol.  This error should normally
                    result in the segmentation of the message into two, the
                    remainder of the recipients to be delivered on a subsequent
                    delivery attempt.  It is included in this list in the event
                    that such segmentation is not possible.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.5.4
Sample Text:        Invalid command arguments
Associated basic status code:  451, 501, 502, 503, 504, 550, 555
Description:        A valid mail transaction protocol command was issued with
                    invalid arguments, either because the arguments were out of
                    range or represented unrecognized features.  This is useful
                    only as a permanent error.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.5.5
Sample Text:        Wrong protocol version
Associated basic status code:  Not given
Description:        A protocol version mis-match existed which could not be
                    automatically resolved by the communicating parties.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.5.6
Sample Text:        Authentication Exchange line is too long
Associated basic status code:  500
Description:        This enhanced status code SHOULD be returned when the server
                    fails the AUTH command due to the client sending a [BASE64]
                    response which is longer than the maximum buffer size
                    available for the currently selected SASL mechanism.  This is
                    useful for both permanent and persistent transient errors.
Reference:          [RFC4954] (Standards Track)
Submitter:          R. Siemborski, A. Melnikov
Change controller:  IESG

Code:               X.6.0
Sample Text:        Other or undefined media error
Associated basic status code:  Not given
Description:        Something about the content of a message caused it to be
                    considered undeliverable and the problem cannot be well
                    expressed with any of the other provided detail codes.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.6.1
Sample Text:        Media not supported
Associated basic status code:  Not given
Description:        The media of the message is not supported by either the
                    delivery protocol or the next system in the forwarding path.
                    This is useful only as a permanent error.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.6.2
Sample Text:        Conversion required and prohibited
Associated basic status code:  Not given
Description:        The content of the message must be converted before it can be
                    delivered and such conversion is not permitted.  Such
                    prohibitions may be the expression of the sender in the message
                    itself or the policy of the sending host.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.6.3
Sample Text:        Conversion required but not supported
Associated basic status code:  554
Description:        The message content must be converted in order to be forwarded
                    but such conversion is not possible or is not practical by a
                    host in the forwarding path.  This condition may result when an
                    ESMTP gateway supports 8bit transport but is not able to
                    downgrade the message to 7 bit as required for the next hop.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.6.4
Sample Text:        Conversion with loss performed
Associated basic status code:  250
Description:        This is a warning sent to the sender when message delivery was
                    successfully but when the delivery required a conversion in
                    which some data was lost.  This may also be a permanent error
                    if the sender has indicated that conversion with loss is
                    prohibited for the message.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.6.5
Sample Text:        Conversion Failed
Associated basic status code:  Not given
Description:        A conversion was required but was unsuccessful.  This may be
                    useful as a permanent or persistent temporary notification.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.6.6
Sample Text:        Message content not available
Associated basic status code:  554
Description:        The message content could not be fetched from a remote system.
                    This may be useful as a permanent or persistent temporary
                    notification.
Reference:          [RFC4468] (Standards Track)
Submitter:          C. Newman
Change controller:  IESG

Code:               X.6.7
Sample Text:        The ALT-ADDRESS is required but not specified
Associated basic status code:  553, 550
Description:        This indicates the reception of a MAIL or RCPT
                    command that required an ALT-ADDRESS parameter
                    but such parameter was not present.
Defined:            [RFC5336] (Experimental track)
Submitter:          Jiankang YAO
Change controller:  IESG

Code:               X.6.8
Sample Text:        UTF-8 string reply is required,
                    but not permitted by the client
Associated basic status code:  553, 550
Description:        This indicates that a reply containing a UTF-8
                    string is required to show the mailbox name,
                    but that form of response is not
                    permitted by the client.
Defined:            [RFC5336] (Experimental track)
Submitter:          Jiankang YAO
Change controller:  IESG

Code:               X.6.9
Sample Text:        UTF8SMTP downgrade failed
Associated basic status code:  550
Description:        This indicates that transaction failed
                    after the final "." of the DATA command.
Defined:            [RFC5336] (Experimental track)
Submitter:          Jiankang YAO
Change controller:  IESG

Code:               X.6.10
Sample Text:        UTF-8 string reply is required,
                    but not permitted by the client
Associated basic status code:  252
Description:        This indicates that a reply containing a UTF-8
                    string is required to show the mailbox name,
                    but that form of response is not
                    permitted by the client.
Defined:            [RFC5336] (Experimental track)
Submitter:          Jiankang YAO
Change controller:  IESG

Code:               X.7.0
Sample Text:        Other or undefined security status
Associated basic status code:  220, 235, 450, 454, 500, 501, 503, 504, 530, 535, 550
Description:        Something related to security caused the message to be
                    returned, and the problem cannot be well expressed with any of
                    the other provided detail codes.  This status code may also be
                    used when the condition cannot be further described because of
                    security policies in force.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.7.1
Sample Text:        Delivery not authorized, message refused
Associated basic status code:  451, 454, 502, 503, 533, 550, 551
Description:        The sender is not authorized to send to the destination.  This
                    can be the result of per-host or per-recipient filtering.  This
                    memo does not discuss the merits of any such filtering, but
                    provides a mechanism to report such.  This is useful only as a
                    permanent error.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.7.2
Sample Text:        Mailing list expansion prohibited
Associated basic status code:  550
Description:        The sender is not authorized to send a message to the intended
                    mailing list.  This is useful only as a permanent error.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.7.3
Sample Text:        Security conversion required but not possible
Associated basic status code:  Not given
Description:        A conversion from one secure messaging protocol to another was
                    required for delivery and such conversion was not possible.
                    This is useful only as a permanent error.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.7.4
Sample Text:        Security features not supported
Associated basic status code:  504
Description:        A message contained security features such as secure
                    authentication that could not be supported on the delivery
                    protocol.  This is useful only as a permanent error.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.7.5
Sample Text:        Cryptographic failure
Associated basic status code:  Not given
Description:        A transport system otherwise authorized to validate or decrypt
                    a message in transport was unable to do so because necessary
                    information such as key was not available or such information
                    was invalid.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.7.6
Sample Text:        Cryptographic algorithm not supported
Associated basic status code:  Not given
Description:        A transport system otherwise authorized to validate or decrypt
                    a message was unable to do so because the necessary algorithm
                    was not supported.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.7.7
Sample Text:        Message integrity failure
Associated basic status code:  Not given
Description:        A transport system otherwise authorized to validate a message
                    was unable to do so because the message was corrupted or
                    altered.  This may be useful as a permanent, transient
                    persistent, or successful delivery code.
Reference:          [RFC3463] (Standards Track)
Submitter:          G. Vaudreuil
Change controller:  IESG

Code:               X.7.8
Sample Text:        Authentication credentials invalid
Associated basic status code: 535, 554
Description:        This response to the AUTH command indicates that the authentication
                    failed due to invalid or insufficient authentication credentials.  In
                    this case, the client SHOULD ask the user to supply new credentials
                    (such as by presenting a password dialog box).
Reference:          [RFC4954] (Standards Track)
Submitter:          R. Siemborski, A. Melnikov
Change controller:  IESG

Code:               X.7.9
Sample Text:        Authentication mechanism is too weak
Associated basic status code: 534
Description:        This response to the AUTH command indicates that the selected
                    authentication mechanism is weaker than server policy permits for
                    that user.  The client SHOULD retry with a new authentication
                    mechanism.
Reference:          [RFC4954] (Standards Track)
Submitter:          R. Siemborski, A. Melnikov
Change controller:  IESG

Code:               X.7.10
Sample Text:        Encryption Needed
Associated basic status code:  523
Description:        This indicates that external strong privacy layer
                    is needed in order to use the requested
                    authentication mechanism.  This is primarily
                    intended for use with clear text authentication
                    mechanisms.  A client which receives this may
                    activate a security layer such as TLS prior to
                    authenticating, or attempt to use a stronger
                    mechanism.
Reference:          [RFC5248] (Best current practice)
Submitter:          T. Hansen, J. Klensin
Change controller:  IESG

Code:               X.7.11
Sample Text:        Encryption required for requested authentication mechanism
Associated basic status code: 524, 538
Description:        This response to the AUTH command indicates that the selected
                    authentication mechanism may only be used when the underlying SMTP
                    connection is encrypted.  Note that this response code is documented
                    here for historical purposes only.  Modern implementations SHOULD NOT
                    advertise mechanisms that are not permitted due to lack of
                    encryption, unless an encryption layer of sufficient strength is
                    currently being employed.
Reference:          [RFC4954] (Standards Track)
Submitter:          R. Siemborski, A. Melnikov
Change controller:  IESG

Code:               X.7.12
Sample Text:        A password transition is needed
Associated basic status code: 422, 432
Description:        This response to the AUTH command indicates that the user needs to
                    transition to the selected authentication mechanism.  This is
                    typically done by authenticating once using the [PLAIN]
                    authentication mechanism.  The selected mechanism SHOULD then work
                    for authentications in subsequent sessions.
Reference:          [RFC4954] (Standards Track)
Submitter:          R. Siemborski, A. Melnikov
Change controller:  IESG

Code:               X.7.13
Sample Text:        User Account Disabled
Associated basic status code:  525
Description:        Sometimes a system administrator will have to
                    disable a user's account (e.g., due to lack of
                    payment, abuse, evidence of a break-in attempt,
                    etc).  This error code occurs after a successful
                    authentication to a disabled account.  This
                    informs the client that the failure is permanent
                    until the user contacts their system
                    administrator to get the account re-enabled.  It
                    differs from a generic authentication failure
                    where the client's best option is to present the
                    passphrase entry dialog in case the user simply
                    mistyped their passphrase.
Reference:          [RFC5248] (Best current practice)
Submitter:          T. Hansen, J. Klensin
Change controller:  IESG

Code:               X.7.14
Sample Text:        Trust relationship required
Associated basic status code:  535, 554
Description:        The submission server requires a configured trust
                    relationship with a third-party server in order
                    to access the message content.  This value
                    replaces the prior use of X.7.8 for this error
                    condition. thereby updating [RFC4468].
Reference:          [RFC5248] (Best current practice)
Submitter:          T. Hansen, J. Klensin
Change controller:  IESG


References
----------
[RFC3463]  G. Vaudreuil, "Enhanced Mail System Status Codes", RFC 3463,
           January 2003.

[RFC3886]  E. Allman, "An Extensible Message Format for Message Tracking
           Responses", RFC 3886, September 2004.

[RFC4468]  C. Newman, "Message Submission BURL Extension", RFC 4468, May 2006.

[RFC4954]  R. Siemborski, Ed., A. Melnikov, Ed., "SMTP Service Extension for
           Authentication", RFC 4954, July 2007.

[RFC5248]  T. Hansen, J. Klensin, "A Registry for SMTP Enhanced Mail System
           Status Codes", RFC 5248, June 2008.

[RFC5336]  J. Yao, Ed., W. Mao, Ed., "SMTP extension for internationalized 
           email address", RFC 5336, September 2008.

(created 2008-05-29)