Running Zimbra in parallel with existing server

[tlxreed]

I've just installed Zimbra on OS X 10.4.8 and it's been working well except for receiving mail from outbound.

What I've done is set up Zimbra on a second system inside our LAN. Our mail is currently hosted on a computer on the same LAN.

The primary mail server is named 'mail.ourdomain.com'. DNS points to our external WAN IP # for mail and a NAT port map forwards SMTP and POP to that machine...pretty typical.

We have internal DNS going via Windows Server 2003. The Zimbra system is named 'zimbra.subdomain.ourdomain.com'. The subdomain isn't authoritative beyond our internal DNS.

I can't shut down our current mail server while we evaluate Zimbra, so I mirror mail from existing accounts to beta accounts on Zimbra, give the user the login credentials and URL and they can get their mail via Zimbra but also still pick it up from the main server using their regular email program if they wish.

The user's return address in their Zimbra preferences is set to their regular email address....user@ourdomain.com. Mail outbound from Zimbra arrives no problem.

The problem is that when someone receives an email from our Zimbra setup and replies to it, the reply goes to user@zimbra.subdomain.ourdomain.com, not user@ourdomain.com.

Also, while our mail server seems to mirror mail pretty well to Zimbra, when mail comes from outside our network, there's some issues with delivery.

Our mail server is SIMS on Mac OS 9. I'm thinking there's some way of setting up the SIMS mail router to ship all mail to 'zimbra.subdomain.ourdomain.com' to the Zimbra system. I also have an external DNS listing in the name server list on the SIMS server, so it could be trying to resolve a nonexistent subdomain as well and failing.

In any event, I'd like to get mail set up this way in an interim fashion so users can have a seamless experience with Zimbra for evaluation purposes. it works 95% at the moment, but that's not quite good enough to have people trust that they are going to get their mail reliably.

Any suggestions appreciated. So far, it's a great setup, just need to iron out a couple of bugs.