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: connect from xbmc.org[188.8.131.52] Jan 6 04:42:37 mail postfix/smtpd: NOQUEUE: reject: RCPT from xbmc.org[184.108.40.206]: 450 4.7.1 <srv1.xbmc.org>: Helo command rejected: Host not found; from=<email@example.com> to=<firstname.lastname@example.org> 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?