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Re: 2821bis and address rewriting (was: Re: Fixing graylisting [was TBR])

2007-11-17 17:19:10

Hi John,
At 08:53 17-11-2007, John C Klensin wrote:
I'm working this weekend on what I hope will be the last version of 2821bis prior to IETF Last Call, so, if you think such a mention would be useful, please propose text and where it should go.

I have not come across any cases where the empty return path is rewritten. If Ned thinks it might be a problem, some text could be added.

In Section

  "In some types of reporting messages for which a reply is likely to cause a
   mail loop (for example, mail delivery and nondelivery notifications), the
   reverse-path may be null (see Section 3.6)."

That provides some guidance on how to avoid a mail loop.

In Section 4.5.5, Messages with a null reverse-path:

  "Implementors of automated email processors should be careful to make
   sure that the various kinds of messages with null reverse-path are
   handled correctly, in particular such systems SHOULD NOT reply to
   messages with null reverse-path."

I read that as a warning about the null reverse-path, i.e. not to rewrite the address or else the message may generate a reply.