On 14.05.22 12:53, Jon LaBadie wrote:
My DNS provider also acts as my backup MX provider.
A lot of mail that would be rejected by the primary
mail server is accepted by the backup provider and
gets through the primary server because the real
source is not checked.
this is a common flaw with backup MX servers and also a reason why many
domains stop using backup MX.
if you aren't interested, is should be easy to stop listing their
mailservers as your backup MX.
Is there a way to inspect mail received via the backup MX
provider differently than other mail?
the question is how do you inspect incoming mail. e.g. you can feed it
into different milters by using smtpd_milter_maps.
filters like spamassassin can do deep header scanning so they can scan IP
addresses from which the backup MX received the mail - you just need to add
the IP of backup MX to trusted_networks and internal_networks.
--
Matus UHLAR - fantomas, uh...@fantomas.sk ; http://www.fantomas.sk/
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