--On Tuesday, May 07, 2013 22:05 +0200 "Rolf E. Sonneveld"
The receiving server can treat the address any way it wants
Agreed, with only one remark: the receiving server that
rewrites the domainpart of RFC5321.MailFrom and/or
RFC5322.From before performing SPF and/or DKIM verification,
loses the ability to _reliably_ perform SPF and/or DKIM
verification after rewriting.
Let me say what may be the same thing a little differently.
The delivery MTA ("receiving server") pretty much has to know
all of the domains under which it will receive mail. Certainly
that is a necessity for any sort of rewriting. If that server
rewrites things incorrectly, or fails to account for the
side-effects of rewriting, various bad things will happen. The
effects on signed headers or fancy attempts to match header
information with additional (non-address, non-MX) information in
the DNS (including, but not limited to SPF and DKIM) are just
some of those bad things.
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