Victor Duchovni wrote: > 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? >
Hi Victor, Just for the record. We use postfix-2.7.3. Relevant part of "postconf -n": smtpd_recipient_restrictions = permit_mynetworks, reject_invalid_helo_hostname, reject_non_fqdn_helo_hostname, reject_non_fqdn_sender, reject_non_fqdn_recipient, reject_non_fqdn_hostname, reject_unauth_destination, [snip] reject_unknown_sender_domain, reject_unknown_reverse_client_hostname, [snip] But I think I got all my questions answered. Thanks, Mikael Bak
