Dnia 4.11.2024 o godz. 10:07:35 Wietse Venema via Postfix-users pisze:
> > if I make a CNAME as,
> >
> > sub.xyz.com CNAME to xyz.net
> >
> > and, xyz.net has its own MX and SPF records.
> >
> > my question is, for this DNS setup, will sub.xyz.com uses MX and SPF of
> > xyz.net for its mail hosting?
> >
> > for example, when external users write to u...@sub.xyz.com, the messages
> > will route to xyz.net's MX server. And, when u...@sub.xyz.com deliver
> > message out, the peer MTA will use xyz.net's SPF for validation. Am I
> > right?
>
> That depends on what the MX record points to. If you're trying to
> do this, then that violates RFC 5321:
>
> example.com. IN A 10.0.0.1
> example.com. IN MX 10 mail.example.com.
> mail.example.com. IN CNAME example.com
>
> (an MX record must not point to a CNAME record).
I guess OP was not asking about MX pointing to CNAME, but rather the
opposite - CNAME pointing to MX (among others). I understand that OP asked
about setup like below (rather exotic, I didn't see it in actual use):
example1.com. IN CNAME example.com
example.com. IN MX 10 mail.example.com.
example.com. IN TXT "v=spf1 a mx ~all"
and the question is, how MX and SPF lookups for example1.com (not
example.com) will behave.
--
Regards,
Jaroslaw Rafa
r...@rafa.eu.org
--
"In a million years, when kids go to school, they're gonna know: once there
was a Hushpuppy, and she lived with her daddy in the Bathtub."
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