Alessandro Vesely writes:
I configured courier esmtpd for blocking spam,
using a MAPS subscription. So far so good.
I also configured a secondary MX for each domain
I host, using such service by an ISP connected
via a different carrier. This also proved quite
However, the two things don't match. Some
spammers blocked by the main MX try the
secondary one, which uses no MAPS lookup,
and succeed. What should I do?
i) try an convince the other ISP to use MAPS
ii) use a global courier filter to scan "Received"
iii) Get rid of the second MX.
A second MX doesn't get you anything unless your primary has been down for
at least 24 hours, and if that happens you'll have other things to worry