I want to be able to access my exchange server at home from behind my firewall. It has a private address assigned. I assume I will have to register a domain name, open the POP3 TCP port on the router, and have a public DNS entry made. Do I use the public address of the router? What type of DNS entry needs to be made?

You would have to have your own domain name as you suspect. You would also have to think about port 25 (smtp) as well as dns (port 53 - udp only) depending on where you are sorting out your dns i.e. hosting your own dns server or receiving it elsewhere. Alternatively (if you believe your firewall and your systems behind it are up to the job, you could set up IIS which would allow you to collect your mail via http. you would need an MX record in your dns so that your network knows where the exchange server is. You would also need a good firewall that allows you to use NAT which would mean your exchange server would in effect have both an external and an internal IP address. I would also ensure you have valid licences for exchange / 2000 etc. just in case you fall into the audit category

Thanks for the response Mick. Im going to register a domain name this week with networksolutions.com. Im using a cheap $39 router from comp-usa but it does the job, i.e. DHCP, NAT and so forth. When I call networksolutions, I assume I will give them the static IP address on the WAN side of the router for the MX and A record correct?

They will give you your external static ip address (or addresses depending on how much you are prepared to spend) e.g 219.34.2.5 On your firewall you would set up the NAT so that all traffic to 219.34.2.5 should be routed to the exchange server on your internal network (e.g. 192.168.1.1) the internal ip address is what goes into the mx record and A record. The firewall should sort the traffic out. Hope it helps. There is more in depth info out there - just google for NAT and firewalls and it should tell you all you need to know

When you mention "they" I assume you mean my ISP will give me a static IP for my router correct? Right now the router is grabbing one through DHCP. Im on a cable modem.