On Fri, Apr 29, 2011 at 09:39:10AM -0400, Wietse Venema wrote:
> > This looks like a Null MX record:
> > http://tools.ietf.org/html/draft-delany-nullmx-00
> >
> > If the domain owner declares that this domain never sends or recieves
> > email, then shouldn't postfix reject the above message with a permanent
> > error?
>
> Anyone can post a draft. That does not mean that they change
> the rules of the Internet.
>
> The SMTP RFC says that the MX record specifies a hostname, and
> there is no RFC that says an empty string is a valid hostname.
This said Null MX records are IMHO a reasonably simple/clean idea. Pity
it never got officially blessed. I seem to recall that same concession
to Null MX records was made in a Postfix release a while back...
20050726
Horror: total rewrite of DNS client error handling because
some misguided proposal attempts to give special meaning
to some syntactically invalid MX hostname lookup result.
Not only that, people expect sensible results with
reject_unknown_sender_domain etc. Files: dns/dns_lookup.c,
smtp/smtp_addr.c smtpd/smtpd_check.c, lmtp/lmtp_addr.c.
[...]
20061227
Bugfix (introduced with Postfix 2.3): the MX hostname syntax
check was skipped with reject_unknown_helo_hostname and
reject_unknown_sender/recipient_domain, so that Postfix
would still accept mail from domains with a zero-length MX
hostname. File: smtpd/smtpd_check.c.
Which release is the OP using?
--
Viktor.
