Internet DRAFT - draft-vaudreuil-1893bis

draft-vaudreuil-1893bis





     Internet Draft                                       Greg Vaudreuil 
     Obsoletes: RFC 1893                             Lucent Technologies 
     Expires in six months                             September 5, 2002 
                                         

                       Enhanced Mail System Status Codes 

                        <draft-vaudreuil-1893bis-03.txt> 

      

  Status of this Memo 

     This document is an Internet-Draft and is in full conformance with all 
     provisions of Section 10 of RFC 2026. 

     This document is an Internet Draft.  Internet Drafts are working 
     documents of the Internet Engineering Task Force (IETF), its Areas, 
     and its Working Groups.  Note that other groups may also distribute 
     working documents as Internet Drafts. 

     Internet Drafts are valid for a maximum of six months and may be 
     updated, replaced, or obsoleted by other documents at any time.  It is 
     inappropriate to use Internet Drafts as reference material or to cite 
     them other than as a "work in progress". 

     The list of current Internet-Drafts can be accessed at
     http://www.ietf.org/1id-abstracts.html

     The list of Internet-Draft Shadow Directories can be accessed at
     http://www.ietf.org/shadow.html


      

  Copyright Notice 

     Copyright (C) The Internet Society (2002).  All Rights Reserved. 

     This Internet-Draft is in conformance with Section 10 of RFC 2026. 

  Abstract 

     This document defines a set of extended status codes for use within 
     the mail system for delivery status reports, tracking, and improved 
     diagnostics.  The in combination with other information provided in 
     the DSN delivery report, these codes facilitate media and language 
     independent rendering of message delivery status. 

      



     Internet Draft      Mail System Status Codes      September 5, 2002 


  Working Group Summary 

     RFC 1893 was a product of the Notary working group.  This document is 
     a revision of that document providing clarifications as necessary to 
     advance to draft standard. 

  Document Conventions 

     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 RFC-2119 [RFC2119]. 

  Table of Contents 

  1.   OVERVIEW ..........................................................3 
  2.   STATUS CODE STRUCTURE .............................................4 
  3.   ENUMERATED STATUS CODES ...........................................7 
    3.1  Other or Undefined Status .......................................7 
    3.2  Address Status ..................................................7 
    3.3  Mailbox Status ..................................................8 
    3.4  Mail system status ..............................................9 
    3.5  Network and Routing Status .....................................10 
    3.6  Mail Delivery Protocol Status ..................................11 
    3.7  Message Content or Message Media Status ........................12 
    3.8  Security or Policy Status ......................................13 
  4.   REFERENCES .......................................................15 
  5.   SECURITY CONSIDERATIONS ..........................................15 
  6.   COPYRIGHT NOTICE .................................................16 
  7.   AUTHOR'S ADDRESS .................................................16 
  8.   APPENDIX A - CHANGES FROM RFC1893 ................................17 
      
























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  1. Overview 

     There is a need for a standard mechanism for the reporting of mail   
     system errors richer than the limited set offered by SMTP and the 
     system specific text descriptions sent in mail messages.  There is a 
     pressing need for a rich machine-readable, human language independent 
     status code for use in delivery status notifications [DSN].  This 
     document proposes a new set of status codes for this purpose. 

     SMTP [SMTP] error codes have historically been used for reporting mail 
     system errors.  Because of limitations in the SMTP code design, these 
     are not suitable for use in delivery status notifications. SMTP 
     provides about 12 useful codes for delivery reports.  The majority of 
     the codes are protocol specific response codes such as the 354 
     response to the SMTP data command.  Each of the 12 useful codes are 
     overloaded to indicate several error conditions each. SMTP suffers 
     some scars from history, most notably the unfortunate damage to the 
     reply code extension mechanism by uncontrolled use. This proposal 
     facilitates future extensibility by requiring the client to interpret 
     unknown error codes according to the theory of codes while requiring 
     servers to register new response codes. 

     The SMTP theory of reply codes partitioned in the number space such a 
     manner that the remaining available codes will not provide the space 
     needed.  The most critical example is the existence of only 5 
     remaining codes for mail system errors.  The mail system 
     classification includes both host and mailbox error conditions.  The 
     remaining third digit space would be completely consumed as needed to 
     indicate MIME and media conversion errors and security system errors. 

     A revision to the SMTP theory of reply codes to better distribute the 
     error conditions in the number space will necessarily be incompatible 
     with SMTP.  Further, consumption of the remaining reply-code number 
     space for delivery notification reporting will reduce the available 
     codes for new ESMTP extensions. 

     The following status code set is based on the SMTP theory of reply 
     codes. It adopts the success, permanent error, and transient error 
     semantics of the first value, with a further description and 
     classification in the second.  This proposal re-distributes the 
     classifications to better distribute the error conditions, such as 
     separating mailbox from host errors. 













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  2. Status Code Structure 

     This document defines a new set of status codes to report mail system 
     conditions.  These status codes are used for media and language 
     independent status reporting.  They are not intended for system 
     specific diagnostics. 

     The syntax of the new status codes is defined as: 

      status-code = class "." subject "." detail  

      class = "2"/"4"/"5"  

      subject = 1*3digit  

      detail = 1*3digit 

     White-space characters and comments are NOT allowed within a status- 
     code.  Each numeric sub-code within the status-code MUST be expressed 
     without leading zero digits. 

     Status codes consist of three numerical fields separated by ".". The 
     first sub-code indicates whether the delivery attempt was successful. 
     The second sub-code indicates the probable source of any delivery 
     anomalies, and the third sub-code indicates a precise error condition. 

     Example:  2.1.23 

     The code space defined is intended to be extensible only by standards 
     track documents.  Mail system specific status codes should be mapped 
     as close as possible to the standard status codes.  Servers should 
     send only defined, registered status codes.  System specific errors 
     and diagnostics should be carried by means other than status codes. 

     New subject and detail codes will be added over time.  Because the 
     number space is large, it is not intended that published status codes 
     will ever be redefined or eliminated.  Clients should preserve the 
     extensibility of the code space by reporting the general error 
     described in the subject sub-code when the specific detail is 
     unrecognized. 

     The class sub-code provides a broad classification of the status. The 
     enumerated values for each class are defined as: 

       2.XXX.XXX   Success 

                 Success specifies that the DSN is reporting a positive 
                 delivery action.  Detail sub-codes may provide 
                 notification of transformations required for delivery. 

       4.XXX.XXX   Persistent Transient Failure 

                 A persistent transient failure is one in which the 
                 message as sent is valid, but persistence of some 

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                 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. 

       5.XXX.XXX   Permanent Failure 

                 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. 

     A client must recognize and report class sub-code even where 
     subsequent subject sub-codes are unrecognized. 

     The subject sub-code classifies the status.  This value applies to 
     each of the three classifications.  The subject sub-code, if 
     recognized, must be reported even if the additional detail provided by 
     the detail sub-code is not recognized.  The enumerated values for the 
     subject sub-code are: 

          X.0.XXX   Other or Undefined Status 

                 There is no additional subject information available. 

          X.1.XXX Addressing Status 

                 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. 

          X.2.XXX Mailbox Status 

                 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. 

          X.3.XXX Mail System Status 

                 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. 

          X.4.XXX Network and Routing Status 

                 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. 


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          X.5.XXX Mail Delivery Protocol Status 

                 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. 

          X.6.XXX Message Content or Media Status 

                 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. 

          X.7.XXX Security or Policy Status 

                 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. 

      


























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  3. Enumerated Status Codes 

     The following section defines and describes the detail sub-code. The 
     detail value provides more information about the status and is defined 
     relative to the subject of the status. 

  3.1 Other or Undefined Status 

          X.0.0   Other undefined Status 

                 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. 

  3.2 Address Status 

          X.1.0   Other address status 

                 Something about the address specified in the message 
                 caused this DSN. 

          X.1.1   Bad destination mailbox address 

                 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. 

          X.1.2   Bad destination system address 

                 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 codes is only 
                 useful for permanent failures. 

          X.1.3   Bad destination mailbox address syntax 

                 The destination address was syntactically invalid.  This 
                 can apply to any field in the address.  This code is only 
                 useful for permanent failures. 

          X.1.4   Destination mailbox address ambiguous 

                 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. 

          X.1.5   Destination address valid 

                 This mailbox address as specified was valid.  This status 
                 code should be used for positive delivery reports. 


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          X.1.6   Destination mailbox has moved, No forwarding address 

                 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. 

          X.1.7   Bad sender's mailbox address syntax 

                 The sender's address was syntactically invalid.  This can 
                 apply to any field in the address. 

          X.1.8   Bad sender's system address 

                 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. 

  3.3 Mailbox Status 

          X.2.0   Other or undefined mailbox status 

                 The mailbox exists, but something about the destination 
                 mailbox has caused the sending of this DSN. 

          X.2.1   Mailbox disabled, not accepting messages 

                 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. 

          X.2.2   Mailbox full 

                 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. 

          X.2.3   Message length exceeds administrative limit 

                 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. 

          X.2.4   Mailing list expansion problem 

                 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. 


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  3.4  Mail system status 

         X.3.0   Other or undefined mail system status 

                 The destination system exists and normally accepts mail, 
                 but something about the system has caused the generation 
                 of this DSN. 

          X.3.1   Mail system full 

                 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. 

          X.3.2   System not accepting network messages 

                 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 
                 permanent transient errors. 

          X.3.3   System not capable of selected features 

                 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. 

          X.3.4   Message too big for system 

                 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. 

          X.3.5 System incorrectly configured 

                 The system is not configured in a manner that will permit 
                 it to accept this message. 














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  3.5 Network and Routing Status 

          X.4.0   Other or undefined network or routing status 

                 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. 

          X.4.1   No answer from host 

                 The outbound connection attempt was not answered, either 
                 because the remote system was busy, or otherwise unable 
                 to take a call.  This is useful only as a persistent 
                 transient error. 

          X.4.2   Bad connection 

                 The outbound connection was established, but was 
                 otherwise unable to complete the message transaction, 
                 either because of time-out, or inadequate connection 
                 quality. This is useful only as a persistent transient 
                 error. 

          X.4.3   Directory server failure 

                 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. 

          X.4.4   Unable to route 

                 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. 

          X.4.5   Mail system congestion 

                 The mail system was unable to deliver the message because 
                 the mail system was congested. This is useful only as a 
                 persistent transient error. 

          X.4.6   Routing loop detected 

                 A routing loop caused the message to be forwarded too 
                 many times, either because of incorrect routing tables or 


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                 a user-forwarding loop. This is useful only as a 
                 persistent transient error. 

          X.4.7   Delivery time expired 

                 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.  

  3.6 Mail Delivery Protocol Status 

          X.5.0   Other or undefined protocol status 

                 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. 

          X.5.1   Invalid command 

                 A mail transaction protocol command was issued which was 
                 either out of sequence or unsupported.  This is useful 
                 only as a permanent error. 

          X.5.2   Syntax error 

                 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. 

          X.5.3   Too many recipients 

                 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. 













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          X.5.4   Invalid command arguments 

                 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. 

          X.5.5   Wrong protocol version 

                 A protocol version mis-match existed which could not be 
                 automatically resolved by the communicating parties. 

  3.7 Message Content or Message Media Status 

          X.6.0   Other or undefined media error 

                 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. 

          X.6.1   Media not supported 

                 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. 

          X.6.2   Conversion required and prohibited 

                 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. 

          X.6.3   Conversion required but not supported 

                 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. 

          X.6.4   Conversion with loss performed 

                 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. 






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          X.6.5   Conversion Failed 

                 A conversion was required but was unsuccessful.  This may 
                 be useful as a permanent or persistent temporary 
                 notification. 

  3.8 Security or Policy Status 

          X.7.0   Other or undefined security status 

                 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. 

          X.7.1   Delivery not authorized, message refused 

                 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. 

          X.7.2   Mailing list expansion prohibited 

                 The sender is not authorized to send a message to the 
                 intended mailing list. This is useful only as a permanent 
                 error. 

          X.7.3   Security conversion required but not possible 

                 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. 

          X.7.4   Security features not supported 

                 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. 

          X.7.5   Cryptographic failure 

                 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. 






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          X.7.6   Cryptographic algorithm not supported 

                 A transport system otherwise authorized to validate or 
                 decrypt a message was unable to do so because the 
                 necessary algorithm was not supported. 

          X.7.7   Message integrity failure 

                 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. 











































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  4. Normative References 

     [SMTP] Postel, J., "Simple Mail Transfer Protocol", STD 10, RFC 821, 
     USC/Information Sciences Institute, August 1982. 

     [DSN] Moore, K., and G. Vaudreuil, "An Extensible Message Format for 
     Delivery Status Notifications", <draft-vaudreuil-1894bis-02.txt>, 
     University of Tennessee, Lucent Technologies, Work-in-Progress. 

  5. Security Considerations 

     This document describes a status code system with increased precision.  
     Use of these status codes may disclose additional information about 
     how an internal mail system is implemented beyond that currently 
     available. 








































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  6. Copyright Notice 

     "Copyright (C) The Internet Society (2002). All Rights Reserved. 

     This document and translations of it may be copied and furnished to 
     others, and derivative works that comment on or otherwise explain it 
     or assist in its implementation may be prepared, copied, published and 
     distributed, in whole or in part, without restriction of any kind, 
     provided that the above copyright notice and this paragraph are 
     included on all such copies and derivative works.  However, this 
     document itself may not be modified in any way, such as by removing 
     the copyright notice or references to the Internet Society or other 
     Internet organizations, except as needed for the purpose of developing 
     Internet standards in which case the procedures for copyrights defined 
     in the Internet Standards process MUST be followed, or as required to 
     translate it into languages other than English.  

     The limited permissions granted above are perpetual and will not be 
     revoked by the Internet Society or its successors or assigns. 

     This document and the information contained herein is provided on an 
     "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING 
     TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT 
     NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN 
     WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF 
     MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE."  

  7. Author's Address 

     Gregory M. Vaudreuil  
     Lucent Technologies 
     17080 Dallas Parkway  
     Dallas, TX 75248-1905 
     Voice/Fax: +1-972-733-2722 
     GregV@ieee.org 




















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  8. Appendix A - Collected Status Codes 

            X.1.0     Other address status 
            X.1.1     Bad destination mailbox address 
            X.1.2     Bad destination system address 
            X.1.3     Bad destination mailbox address syntax 
            X.1.4     Destination mailbox address ambiguous 
            X.1.5     Destination mailbox address valid 
            X.1.6     Mailbox has moved 
            X.1.7     Bad sender's mailbox address syntax 
            X.1.8     Bad sender's system address 
      

            X.2.0     Other or undefined mailbox status 
            X.2.1     Mailbox disabled, not accepting messages 
            X.2.2     Mailbox full 
            X.2.3     Message length exceeds administrative limit. 
            X.2.4     Mailing list expansion problem 
      

            X.3.0     Other or undefined mail system status 
            X.3.1     Mail system full 
            X.3.2     System not accepting network messages 
            X.3.3     System not capable of selected features 
            X.3.4     Message too big for system 
      

            X.4.0     Other or undefined network or routing status 
            X.4.1     No answer from host 
            X.4.2     Bad connection 
            X.4.3     Routing server failure 
            X.4.4     Unable to route 
            X.4.5     Network congestion 
            X.4.6     Routing loop detected 
            X.4.7     Delivery time expired 
      

            X.5.0     Other or undefined protocol status 
            X.5.1     Invalid command 
            X.5.2     Syntax error 
            X.5.3     Too many recipients 
            X.5.4     Invalid command arguments 
            X.5.5     Wrong protocol version 
      

            X.6.0     Other or undefined media error 
            X.6.1     Media not supported 
            X.6.2     Conversion required and prohibited 
            X.6.3     Conversion required but not supported 
            X.6.4     Conversion with loss performed 
            X.6.5     Conversion failed 
      



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            X.7.0     Other or undefined security status 
            X.7.1     Delivery not authorized, message refused 
            X.7.2     Mailing list expansion prohibited 
            X.7.3     Security conversion required but not possible 
            X.7.4     Security features not supported 
            X.7.5     Cryptographic failure 
            X.7.6     Cryptographic algorithm not supported 
            X.7.7     Message integrity failure 
      

      

      

      

      

      

      

      

      

      

      

      

      

      

      

      

      

      

      

      

      

      


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  9. Appendix B - Changes from RFC1893 

     Changed Authors contact information. 

     Updated required standards boilerplate. 

     Edited the text to make it spell-checker and grammar checker 
     compliant. 

     Modified the text describing the persistent transient failure to more 
     closely reflect current practice and understanding. 

     Eliminated the restriction on the X.4.7 codes limiting them to 
     persistent transient errors. 

      



































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