You can run SMTP from your own computer but you may get in trouble with your ISP for running a server program.
First, you would need to find out the address to your computer.
To find out your numeric IP, go to START -> Run and type "cmd" to open a command prompt. Now type "ipconfig" and hit Enter. You should be shown something like this:
IP Address. . . . . . . . . . . . : 12.34.56.78
If you have a router this isn't as easy. Your IP will show up as "192.168.x.x". You need to access the router config panel and see what external (WAN) IP is assigned. You will need to set up a "port forward" for port 25 to your internal IP.
Your ISP could assign IPs dynamically. If so, your address/IP might change if the power goes out or you disconnect the router/your computer for extended periods of time.
If you have a firewall (Windows XP) you will have to allow access to port 25.
To prevent being used for spam, configure the SMTP program so that all mailing is restricted except for authorized users and set up an account.
To prevent detection from your host, you should probably change the port to something other than 25. Try something not listed as reserved on
this page.