I'm just curious if it is possible to modify the postfix settings such that incoming messages will have the sub-domain stripped out of all message headers, without affecting mail delivery.

For example, to test our Zimbra install without affecting our current mail setup, we've given it the domain zimbra.ourdomain.com. All messages are sent to @zimbra.ourdomain.com addresses. Our edge MTA routes messages accordingly (@ourdomain.com to our production mail server, @zimbra.ourdomain.org to our Zimbra server, etc).

Outgoing mail has all headers modified to remove zimbra so that fcash@zimbra.ourdomain.com becomes fcash@ourdomain.com. This is done via canonical_senders in main.cf.

Incoming mail has all headers modified to add zimbra based on the canonical mappings so that fcash@ourdomain.com becomes fcash@zimbra.ourdomain.com and gets delivered to the correct server.

Is it possible to edit the postfix config on the zimbra server to strip out the "zimbra", and still have it delivered to the correct account/mailbox? Will it cause any issues if we do this? Is the domain part of the username? Is it as simple as editing the postfix config on the zimbra server?

Thought I'd check before I go mucking around with our server. Better to get it right from the get go, even if it is a test server.