I continue to think the problem is associated specifically with an msn.com address. Microsoft first used msn.com, then hotmail.com, and now live.com. Some of us still have the original.
I actually found a workaround that appears to do the minimum necessary:
When adding an email account on Windows Mobile 6.5, its first question asks for your email address. Do not enter your msn.com address, but rather something else like
dummy@dummy.com. WM6.5 will then give up and let you set all parameters manually. These appear to work acceptably for me:
Protocol: POP3
Incoming mail server: pop3.live.com
Outgoing mail server: smtp.live.com
Authentication in both directions
Username: <full msn.com address>
Password: <msn.com password>
You can go back and change the dummy address later. (You will need to do so, because that gets into your outgoing emails as your return address.)
The bottom line is that
Windows Mobile 6.5 doesn't want to support msn.com, but can be forced to do so.