Hi all,

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 useful.

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?

TIA Ale