Hi, We have a server running Postfix, with mailing lists run by Mailman, for a local domain. This server receives mail from an upstream cloud-based server for all recipients not on the cloud-based server (the idea being that any user not on the cloud server is a mailing list). The mail is relayed to the mailing list server via another internal postfix server. Mail that is sent to users that don't exists and are not mailing lists ends up on the relay server, as it gets rejected with 'user unknown' by the mailing list server when Postfix sees that it is not in the local_recipient_maps. This ends up clogging up the relay server as it tried to deliver (mostly spam) back to the originators. I think the best solution may be to have the mailing list server to accept mail received via SMTP that it doesn't have a local_recipient_map for, and then forward it to /dev/null, but I'm not quite sure how to do this. Or perhaps there is a way on the relay server to delete mail it gets a 550 unknown response for.
Any suggestions as to the best way to do this? Thanks, Cam
