Good morning all,

we've got a somewhat eccentric setup for our mailman installation, and we're having difficulty getting some of the settings to work properly, so I'm hoping some one has some insight.

Our server machine is hidden behind our firewall, with the actual machine name not availble via external DNS) and all the mail is being routed through an Exchange server. So mail to list@domain.com hits our exchange server, which sends it on to lists@listserver.domain.com

The problem we're having is that if the mailman domain of the list is listserver.domain.com then spamfilters start to flag the mail since it looks like spoofing/malformed headers and so on. If the mailman domain is just domain.com then postfix rejects it with an unknown local recipient error. I though I might be able to just tweak the incoming mail headers in postfix via header_checks but that's not working, either because I've got the wrong check or it's the wrong approach, or both.

postfix relay_domains might do it, I think, but if it maps listserver.domain.com to domain.com that would break the listserver domain mailing lists (I think).

Is there a canonical way to do this and/or have I missed some obvious configuration option in either mailman or postfix?

Kind regards,

Jeff Berry jeff.berry@mrc-cbu.cam.ac.uk