http://www.sendmail.org/ is a Linux SMTP server (just had to include that LOL)

For an IMAP server, check out these links. Maybe one of them will be useful to ya:
http://www.imap.org/
ftp://rtfm.mit.edu/pub/usenet/comp.a...mailclient-faq

My solutions to my problem was to back you to Red Hat 7.3 and let the system install it for me

I use Courier IMAP, but it only works if you?re using maildirs, qmail?s mail directory format (although I think it?s an option for postfix as well), for local delivery.

I?ve also heard that Cyrus IMAP is a good IMAP server, although I can?t say myself.

I would, however, recommend not using the UW imap server that comes stock in RedHat (and perhaps other distros). It sucks.