Are there any control panels or other programs that have something to do with changing locations?
Mac computers have something called the Location Manager which does exaclty what you need. You set up all of your network and email settings for home, save it as one profile, and then create one profile for each location or network you will be connecting to. All you need to do is tell the computer which location you are at, and it will adjust the email and network settings accordingly.
I thought WindowsXP had something similar, but I don't have a laptop myself. My girlfriend does have one though, so maybe I can find out tonight.
This may not directly solve your problem, but it maybe it will you an idea of what to look for.
goates
PS - If you play around with your own mail server, make sure it is properly secured. Otherwise anyone on the internet could use it to relay SPAM.