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Re: draft-klensin-rfc2821bis-04: VRFY and EXPN syntax

2007-07-15 00:11:49

At 17:09 14-07-2007, Peter J. Holzer wrote:
Yes. When I did some experiments with SMTP callbacks some time ago, I
found that most MTAs return that (I wonder what advertising the VRFY
capability in the EHLO response and then returning a useless result is
supposed to accomplish ...), but even worse, some expected the email
address in angle brackets and some without, so you would get false
negatives unless you tried both ... Too much trouble for too little

It might be better to list VRFY in the EHLO response only if the command is supported by the installation. The "if EXPN is supported, it MUST be listed as a service extension in an EHLO response." would still apply.

Draft-04 does not specify that angle brackets must be used. The example in that section could be clearer if it was:

      C: VRFY smith
      S: 553 User ambiguous


      C: VRFY smith
      S: 553- Ambiguous; Possibilities are
      S: 553-Joe Smith <smith(_at_)example(_dot_)com>
      S: 553-Harry Smith <smith(_at_)example(_dot_)net>
      C: 553 Melvin Smith <smith(_at_)example(_dot_)org>


      C: VRFY smith
      S: 553-Ambiguous; Possibilities
      S: 553- <jsmith(_at_)example(_dot_)com>
      S: 553- <hsmith(_at_)example(_dot_)com>
      S: 553 <dweep(_at_)example(_dot_)com>


       C: VRFY <smith(_at_)example(_dot_)com>
       S: 250 smith <smith(_at_)example(_dot_)com>


       C: VRFY smith(_at_)example(_dot_)com
       S: 250 smith <smith(_at_)specific(_dot_)example(_dot_)com>

The before last example is for a user name and domain. Although it is accepted by some implementations, and I believe, readily used, it does not fit the description for a string as a user name.