Debian email server setup - scenario

[conflict]

I am a student involved in an network/computer security organization on campus. We are having an academic cyber security competition where a red team will attempt to take down services of various blue teams (student teams).

It is an uptime competition where services are scored based on availability. I am looking to setup a practice network (including this Debian email server) for this event and am looking for an optimal Debian email server setup that is also secure or can be made secure. I have looked into various packages like postfix, devcot, courier, squirrelmail (For web) , etc
I would also need IMAP/POP3 over SSL capabilities.
This server needs to be able to send/receive email within a LAN and does not have to traverse the internet.

Again the focus here is on security and uptime.
This is also a timed event.
I'm just looking for info on the Email server as it is currently. For any changes to network architecture (such as putting the email server in the DMZ), we have to write a change request and hope its approved.

Any suggestions on what to use would be most appreciated and I will get working on building this server within the next few days.

[atreyu]

Hi,

It sounds like you already know what you want to do. It is a complicated process setting up a secure mail server, though. I've used the following guide before, with success. As a bonus, it is Debian-specific:

Debian GNU/Linux 6.0 Squeeze - MAIL Server - Install/Configure Postfix : Server World

If you are concerned about protecting yourself from unwanted snoopers, you ought to consider implementing a firewall (iptables), too.

[conflict]

Sounds good, just confirmed what I thought. Thanks!