smtpd_helo_restrictions = ..., reject_unknown_helo_hostname occasionally rejects mail I care about, how to handle?

Posted by lkraav on Server Fault See other posts from Server Fault or by lkraav
Published on 2013-01-06T18:56:08Z Indexed on 2013/11/10 22:02 UTC
Read the original article Hit count: 296

Filed under:

linux

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postfix

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administration

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spam-prevention

I have configured my postfix as follows:

smtpd_helo_restrictions = permit_sasl_authenticated, permit_mynetworks, reject_unknown_helo_hostname

This is working well because most spambots don't seem to have correct reverse lookups. But every once in a while I run into mail I care about getting reject, because the mail source server admin doesn't care about configuring his server correctly.

For example here the server introduces itself as "srv1.xbmc.org" which has no DNS record and fails my basic check.

Jan  6 04:42:36 mail postfix/smtpd[660]: connect from xbmc.org[205.251.128.242]
Jan  6 04:42:37 mail postfix/smtpd[660]: NOQUEUE: reject: RCPT from xbmc.org[205.251.128.242]: 450 4.7.1 <srv1.xbmc.org>: Helo command rejected: Host not found; from=<[email protected]> to=<[email protected]> proto=ESMTP helo=<srv1.xbmc.org>

I have tried to contact the server admin several times, but there is no response. What is the optimal way to handle this from my side? Is adding these "special" hosts to mynetworks = my only option? Is perhaps my whole smtpd_helo_restrictions setup wrong in some significant way?

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