What do I need to setup for this: 2 mail servers at the same time

[charlier]

Okay,

I'm almost ready to roll this out and start some serious testing. I've just found one more problem that I'm not sure how to proceed on.

I want to keep 2 servers up. My current production Postfix / Dovecot / Mbox setup. And then my dev zimbra box that I'm slowly trying to migrate to.

So I'm not sure if I need to relay my mail to my outside MX's or if there is a smarter way to do this. But my goal is to transition to the dev zimbra box, and use this full time.

Part 2, is that when I send mail from zimbra, I get errors that the user doesn't exist yet (locally, because I haven't added them yet), and it doesn't send the mail to my production server.

Whats the easiest way to solve this?

My guess is to set this up to relay mail to my outside MX's that then they forward the mail down. (This I know works, but looking for a better way for zimbra to know to send mail along if the user isn't on the server yet).


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How my mail comes in (it's complicated, don't ask, I'm working on it ).

Outside MX's (these have aliases to forward mail all over the place)
V
For end users email, it T's off to our spam hardware and now, the zimbra server
V
> goes direct to our zimbra server
> Spam Hardware forwards to our Linux / Postfix setup

[phoenix]

Start with the Split Domain article and see if that answers your questions.