I'm thinking of installing Zimbra onto a Plesk server - Plesk currently controls the mail subsystem.

I know Zimbra prefers to install it's own smtp, pop and imap servers; but would it be possible for me to keep my existing setup, and just use Zimbra as a glorified webmail client? Or would I be better off disabling all mail-related features in Plesk, and letting Zimbra take control? (the disadvantage I can see to this is the need to then migrate mail and accounts into Zimbra)

Any advice greatly appreciated!