Transport configuration question

[jroberts235]

I have a Zimbra 5.0.5_GA_2201, an edge MTA running Postfix-2.3.3-2 and a mailman server, all seperate machines on the same network.

All mail from outside goes to my edge MTA where I have a virtual_aliases and a transport file to direct mail to either Mailman or Zimbra. The Zimbra server handles mail for domain.com and Mailman, lists.domain.com.

My Zimbra server uses this MTA to relay ALL mail for it. So that if a Zimbra user sends mail, even if it is for local delivery, it first sends it to the MTA and then the MTA returns it to Zimbra for delivery or sends it to mailman. This is needed so that, emails to the mailing list, get expanded and delivered to mailman. If I did not do it this way, then mail to alias@domain would not get recognized as an alias for a mailing list and Zimbra would check to see if it is a local user, which it is not and therefore would reject it. This seems a little waistful, but it works and the MTA seems to not be bothered by the extra traffic.

It all worked as planned until I added IMAP support for my users. They connect to Zimbra IMAP port, NOT the edge MTA's, so that they can be authenticated against the Zimbra user list.

For some reason Zimbra is not routing any mail recieved via IMAP to the edge MTA, so that mail to mailing lists is failing to reach Mailman.

Should I be looking into duplicating the transport and alias tables from the MTA on Zimbra?

Could I create a domain in Zimbra called lists@domain.com and then add a line to the existing Zimbra transport table to route all mail to Mailman?

Thanks to the forum members in advance for all help, and also for making this forum such a valuable resource.