Split domain migration

[zimkeeps]

New to zimbra, and so far it looks awesome and would love to migrate over all my users to it if the trial period works out.


But i have a general question on split domain/maquerading and best practice.


Currently, i have a set of postfix relay and spam hosts at the front end handing my mail traffic. These have a sync over aliases file that go to either three locations depending on the alias ( exchange, imap server, mailing list server). All of them use the front end boxes as their external relay.

In the case of exchange, the exchange domain is box.domain.com, the aliases on the front end boxes point to user@box.domain.com, and exchange is set to masquerade for domain.com, to the point that box.domain.com is never seeing by the outlook user as their from address, they only see user@domain.com. Users not on exchange, exchange forwards back up to the relay boxes, which then forward to the appropriate system(s).


How would i achieve the same setup on zimbra?

I currently set it up as having one domain, zimbra.domain.com. Masquerading as per the ManagingDomains wiki as domain.com. And then i set my external MTA to be the front-end boxes. So while the box acknowledges domain.com, it gets forwarded to the external MTA, not to local. ( i even tried setting the canonical address field )

Is the only way to create domain.com in zimbra? how would it handle accounts for domain.com that are not yet created in zimbra? will it try the external mta, or bounce them?

( eventually i think i'll have zimbra manage the aliases, and hook up the front end boxes via ldap to zimbra, but not yet )