We recently added a Windows 2003 Server to our system, which includes
Exchange, Microsoft's email server software. Right now we have
ISP-based POP email, and the windows server sits behind our BM 3.6
firewall with only a private-side address.

We are planning to replace the 3.6 server shortly with a 3.8 server.

Can this work or does the Exchange server need to have a public address?
Would NAT suffice? We do have unused public IP's we could assign to it.
Would it be as simple as asking our ISP to point the email domain to the
NATted public address?

Many thanks in advance.