John C Klensin <[email protected]> wrote: > > Actually, something else just occurred to me. I don't think it > changes the "verified" answer and I can't remember why Randy and > I left the prohibition there when it was removed from SMTP.
The text in section 8.7 that I reported the problem with is new in RFC 6409 - it was not present in RFC 4409. It isn't something you "left". It looks like it was added to provide more rationale for the MAY provision in that section. The MAY is there (I think) because Sendmail does the rewrite that the MAY permits, and most other MTAs/MSAs do not. In RFC 4409 the rationale simply discourages MSAs from rewriting, which is consistent with the change in DRUMS several years earlier to remove CNAME canonicalization, and which agrees with the argument you laid out in the message I am replying to. The error is that RFC 6409's expanded rationale is completely backwards. It makes it sound like the MAY is giving MSAs permission not to rewrite when it would otherwise be required by RFC 5321. However there is no such requirement in RFC 5321, and the MAY is actually giving MSAs permission to rewrite even though it is not necessary and can be harmful. So the point of my suggested replacement text is to explain the historical background which has led to some MSAs doing a rewrite which we now consider to be misguided. Yes it is suboptimal - it could indeed be improved by expanding pronouns as Randall suggested, and I should not have left out the perfectly correct sentences that came from RFC 4409. Tony. -- f.anthony.n.finch <[email protected]> http://dotat.at/ Sole: West or northwest 4 or 5, increasing 6 at times. Moderate. Showers. Moderate or good. _______________________________________________ yam mailing list [email protected] https://www.ietf.org/mailman/listinfo/yam
