IMAP- how to protect a server?

["Aaron D. Turner" <aturner () vicinity com>]

Currently our company uses POP3 for email (yuck) with a box in the DMZ
proxying traffic to the internal mailserver through a FW-1 box.  

Anyways, I'm trying to come up with the best way to deploy an IMAP/SSL
server to replace POP3.

The thing is that we consider are trying our best to secure the email
from would-be unfriendlies, and I'd rather not have the mail folders
sitting in the DMZ.  And of course, I don't want to punch a hole
through the firewall and put the IMAP server on the internal network.
NFS between a IMAP server in the DMZ and the mail folder server 
in the Internal net isn't a good idea either.

So what is the 'proper' way of doing this?  

Also, can anyone recommend a powerful, secure, compliant IMAP server?

Thanks.

-- 
Aaron Turner, CNE   aturner () vicinity com  650.237.0311 x252
Network Engineer    Vicinity Corp.        http://www.vicinity.com
Email-to-page: 6505721411.1146752 () pagenet net [Subject & Body sent]