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"
headers, recognize my secondary MX's header,
lookup the original IP on MAPS and block the
message on positive responses.
I'd write a C thing for doing (ii), unless someone
has a better idea, or already wrote it. Anyone out
there? And, would anybody be interested in
co-authoring and test that thing?