I have developed a software package that allows your station to be an email gateway, all that's required is a TNC and your computer connected to the internet.
I have used it to send/receive email while mobile (connect to my home station and start typing). It's authenticated by callsign and connects to the user's POP3/SMTP server, or if you host email like me you can create user accounts on your server to provide email access to whomever you like.
It's been tested with Comcast and Windows Exchange Server 2003, and the only TNC I have tested it with is a Kantronics KPC-3. It should work with any Kantronics TNC as the command structure is the same, if you want to see a little preview you can check it out a http://odqmail.ianthurston.com
. I will have a trial version available for download shortly, just check back in to the website for updates.
I'd appreciate any comments, either here or using the website feedback form. You can also do callbook lookups as well. The interface looks like a standard BBS interface with comprehensive help and features.