It appears many Mail users are having authentication problems in which they are prompted for the username and password every time a message is sent (either manually ...

I'm not sure I understand the pertinent details of your post, but if you are using AOL as your ISP, this is why your e-mail receives the suffex reflecting the AOL mail server (SMTP).

My school uses an IMAP email system that I connect to via Outlook. However, they only allow me to use their outgoing mail server when I access my email from within their domain. That server is ...