I have an old postfix/courier imap/spamassassin email server running on Red Hat Linux 9.

It's not running too well right now and we want to move to newer hardware and Zimbra.

I'm just worried on how the best plan of attack should be. How can I migrate all email from linux to the new Zimbra? Can I migrate passwords on the acounts as well? It's currently authenticating all users via the /etc/passwd file.

Just want some examples and tips on the best way to go about this upgrade.