File: rfc1893.txt

package info (click to toggle)
doc-rfc 20181229-2
  • links: PTS, VCS
  • area: non-free
  • in suites: buster
  • size: 570,944 kB
  • sloc: xml: 285,646; sh: 107; python: 90; perl: 42; makefile: 14
file content (843 lines) | stat: -rw-r--r-- 28,218 bytes parent folder | download | duplicates (12)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843






Network Working Group                                        G. Vaudreuil
Request for Comments: 1893                         Octel Network Services
Category: Standards Track                                    January 1996


                   Enhanced Mail System Status Codes

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

1.   Overview

   There currently is not a standard mechanism for the reporting of mail
   system errors except for 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 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 each 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



Vaudreuil                   Standards Track                     [Page 1]

RFC 1893                Mail System Status Codes            January 1996


   space for delivery notification reporting will reduce the available
   codes for new ESMTP extensions.

   The following proposal 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.

2.   Status Codes

   This document defines a new set of status codes to report mail system
   conditions.  These status codes are intended to be 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.

   The codes 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.




Vaudreuil                   Standards Track                     [Page 2]

RFC 1893                Mail System Status Codes            January 1996


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

    2.X.X   Success

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

    4.X.X   Persistent Transient Failure

       A persistent transient failure is one in which the message as
       sent is valid, but some temporary event prevents the successful
       sending of the message.  Sending in the future may be successful.

    5.X.X   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.X   Other or Undefined Status

          There is no additional subject information available.

       X.1.X   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.X   Mailbox Status

          Mailbox status indicates that something having to do with the
          mailbox has cause this DSN.  Mailbox issues are assumed to be
          under the general control of the recipient.






Vaudreuil                   Standards Track                     [Page 3]

RFC 1893                Mail System Status Codes            January 1996


       X.3.X   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.X   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.

       X.5.X   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.  Mail
          delivery protocol issues may be controlled by many parties
          including the originating system, destination system, or
          intermediate system administrators.

       X.6.X   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 whom must support a common set of supported
          content-types.

       X.7.X   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.





Vaudreuil                   Standards Track                     [Page 4]

RFC 1893                Mail System Status Codes            January 1996


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.



Vaudreuil                   Standards Track                     [Page 5]

RFC 1893                Mail System Status Codes            January 1996


       X.1.5   Destination address valid

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

       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.







Vaudreuil                   Standards Track                     [Page 6]

RFC 1893                Mail System Status Codes            January 1996


       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.

   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.








Vaudreuil                   Standards Track                     [Page 7]

RFC 1893                Mail System Status Codes            January 1996


       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 which will permit
          it to accept this message.

   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.



Vaudreuil                   Standards Track                     [Page 8]

RFC 1893                Mail System Status Codes            January 1996


          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 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.  This is useful only as a persistent
          transient error.

   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.




Vaudreuil                   Standards Track                     [Page 9]

RFC 1893                Mail System Status Codes            January 1996


       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.

       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 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



Vaudreuil                   Standards Track                    [Page 10]

RFC 1893                Mail System Status Codes            January 1996


          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 permanant
          error if the sender has indicated that conversion with loss
          is prohibited for the message.

       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.







Vaudreuil                   Standards Track                    [Page 11]

RFC 1893                Mail System Status Codes            January 1996


       X.7.4   Security features not supported

          A message contained security features such as secure
          authentication which 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.

       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.

4.   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", RFC 1894, University of
       Tennessee, Octel Network Services, January 1996.

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.

6.   Acknowledgments

   The author wishes to offer special thanks to Harald Alvestrand, Marko
   Kaittola, and Keith Moore for their extensive review and constructive
   suggestions.




Vaudreuil                   Standards Track                    [Page 12]

RFC 1893                Mail System Status Codes            January 1996


7.   Author's Address

   Gregory M. Vaudreuil
   Octel Network Services
   17060 Dallas Parkway
   Suite 214
   Dallas, TX 75248-1905

   Voice/Fax: +1-214-733-2722
   EMail: Greg.Vaudreuil@Octel.com









































Vaudreuil                   Standards Track                    [Page 13]

RFC 1893                Mail System Status Codes            January 1996


8.   Appendix - 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





Vaudreuil                   Standards Track                    [Page 14]

RFC 1893                Mail System Status Codes            January 1996


       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











































Vaudreuil                   Standards Track                    [Page 15]