[69305] in North American Network Operators' Group
Re: Mailserver requirements
daemon@ATHENA.MIT.EDU (Valdis.Kletnieks@vt.edu)
Mon Apr 5 17:22:50 2004
To: Arnold Nipper <arnold@nipper.de>
Cc: NANOG <nanog@nanog.org>
In-Reply-To: Your message of "Mon, 05 Apr 2004 23:03:05 +0200."
<4071C989.4040807@nipper.de>
From: Valdis.Kletnieks@vt.edu
Date: Mon, 05 Apr 2004 17:21:21 -0400
Errors-To: owner-nanog-outgoing@merit.edu
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On Mon, 05 Apr 2004 23:03:05 +0200, Arnold Nipper <arnold@nipper.de> said:
> Today I run across a MTA which refused to accept mail because it could
> not detect an MX record for the reverse mapping of the IP address of the
> server which tried to deliver mail. Is this correct?
Depends on your definition of "correct". Checking that there's a PTR and A
record that match has become common, although not strictly standard. Checking
that said PTR points to a hostname that has an MX is certainly "way out there".
> Or: if A is the IP Address of server trying to deliver mail, does
> mx(reverse(A)) have to exist?
There's no RFC requirement that an MX exist at all (only that you check for
an MX before using the A record).
The last 2 AOL boxes I got mail from were omr-m07.mx.aol.com and rly-ye05.mail.aol.com.
I'm not seeing an MX for either of those.
Draw your own conclusions as to whether a Randy Bush quote is needed....
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