On Fri, Nov 28, 2014 at 08:11:54AM -0500, Wietse Venema wrote:
> Dirk St?cker:
> > For some subdomains when switching from catchall to individual settings I
> > simply set a CNAME to another name with correct MX settings
> >
> > name.domain.tld --> mail.domain.tld (containing A,AAAA and MX)
> >
> > It worked for many servers, but some started to deliver mail to
> > u...@mail.domain.tld instead of u...@name.domain.tld. They shouldn't
> > rewrite the mail address, should they?
>
> That goes back to RFC 821. RFC 2821 explicitly allows aliases in
> commands. Postfix still has a now-unused smtp_unalias module to
> replace domain name aliases in MAIL FROM and RCPT TO.
Very old Sendmail config files used to by default canonicalize (aka
unalias) the domain part of recipient addresses so as to conform
to RFC 821. This was the right thing to do some 20+ years ago.
Most Sendmail systems no longer do this, but perhaps some operators
never got the message. Don't unalias the recipient domain.
--
Viktor.
