Recomendations?

["David Busby" <busby pnts com>]

List,
    I need to setup a mail server for my office, I'd like to use some
packages to make my life easier.
What packages do I need to have SMTP, POP3, IMAP and some Web based Mail
interface all work together?  I would also like the server to function as
primary MX for a few domains (virtual hosting?), and a secondary for a few
other domains.  I was thinking Postfix for SMTP, Courier for POP3/IMAP but
web mail I don't know.  How do I sync the usernames/passwords between the
three softwares?

Thanks in advance.

/B