Not sure if there are any MTA's ported to Maemo or not. You might be able to just 'apt-get install' either postfix, or sendmail from the command line as root. As for installation instructions - both postfix and sendmail are heavily documented and supported in their respective communities.

Issues I see are:

1. A mail server should be connected all the time - this means power cord in, and turned on all the time.

2. What about backup, virus scanning, spam filtering. You would need something like ClamAV and Spamassassin running via mailscanner for example.

I also have my own domain, and I was running a postfix/courier-imap/mailscanner installation on an Ubuntu 6.06LTS home server. I had it running for over a year, and I found it to be a bit of a pain after a while. Ensuring mail is backed up (via RAID, and rsync), keeping on top of Antivirus, etc.

So, I recently switched my domain's mail to Google Apps (www.google.com/a). As long as you control your MX records, you can use their service, and benefit from their venerable mail system (now with IMAP). This has really reduced my daily headache, and has given me alot more functionality than I had before.

As for webpages, yes, there is an apache port now on maemo.org, as well as a few others. Again, the respective communities for the webservers have good documentation on setting them up. Google Apps also will serve your webpage for you if you chose to have them handle the mail for your domain !!

Ask more questions if you want to proceed down the path of setting up the mail server on the 770. I'm more than happy to lend a helping hand.