S Moonesamy <sm+ietf(_at_)elandsys(_dot_)com> wrote:
At 08:05 22-05-2014, Ned Freed wrote:
If memory servers, ancient versions of sendmail supported this and
actually rewrote such aliases.
This is a configurable option in sendmail to do the rewrite.
I was looking at this yesterday. Sendmail has a DontExpandCnames option
(off by default so it does CNAME-based rewriting by default) but as I
understand it this controls the routing of outgoing mail and does not
affect which domains Sendmail will consider to be local and which it will
accept in non-relay RCPT commands.
The key thing about John's suggestion is that an MX MTA would accept mail
to domains for which it does not have any explicit configuration but which
have a CNAME pointing to an explicitly configured domain.
(Aside: The DontExpandCnames option has amusingly backwards documentation
which seems to date from the late 1990s: "This currently violates the
published standards, but the IETF seems to be moving toward legalizing
this.")
Tony.
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