On 16/10/2020 22:04, David Wells wrote:
I have a postfix-3.3.2 installation (installed from source on
slackware 14.2 from the slackbuilds package) that does rbl checks in
the smtpd_recipient_restrictions section. I have been seeing an
increasing amount of spam coming in so I added more reject_rbl_client
instances listing more and more rbl servers. However I still am seeing
large ammounts of spam getting through and I have checked several
mails that have come in using http://multirbl.valli.org/ and the
servers from which they arrive are listed in at least one of these rbl
checks, most times in more than one. Is there a way to debug why these
mails are getting through even though they come from an rbl
blacklisted server?
On top of the excellent advice already given, another possible cause:
you are not running a local DNS server and so your lookups are passing
through an external one (such as your ISP's) and are RBLs are refusing
to give (useful) responses because the source IP that they see (of the
external DNS server) doesn't look private or has submitted too many
lookups.
