I took a quick luck at the issues. Some are non-issues, such as AOL Mail and Netscape WebMail Accounts. What is said is incorrect, and, thus misleading.
In first there has been no netscape.net mail, web or otherwise for nearly two years. The server is aim.com. As for AOL webmail, accounts are set up like aim.com. The difference is that NS7.x had a quick way to set up the accounts. Seamonkey, and other programs use a slightly different method, but everything is basically the same.
To receive mail, one select new mail accounts, put in the same info as in NS7.2. Then there is the choice, like for other mail accounts. Imap should be chosen. I don't believe in Global Settings, since it piles up all mail in one folder, so I uncheck that box. The servers are imap.aim.com or imap.aol.com. I use my ISP SMTP to send such mail, but one can set up secondary SMTPs for the two types of accounts, using port 587.
In server settings since the account have been set up as IMAP, it will use port 143 to receive mail. I have not had either NS6 nor 7, as the "issues " imply that they are necessary.
By using my ISP SMTP, I can interact with the sender perfectly well.
UserAgent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9b3pre) Gecko/2008010500 SeaMonkey/2.0a1pre