How to fix AOL/AIM/Netscape mailbox "Offline"

Ever since OS X Yosemite, I have had my AIM mailbox frequently going "offline". (My account was converted from Netscape to AIM, but I see that many AOL users also have the same problem.) If you have the same problem, try set up account without selecting AOL.

Instead, select the vanilla "Add Other Account -> Mail account", then entered you E-mail address.

In the past, I tried "Rebuild", delete account then add back, etc., like a million times. The service would restore for a weeks, sometimes days, then it will go "offline". It was getting worse in recent months and finally, "Rebuild" stops rebuilding; any other magic I tried could sustain for less than a day. "Connection Doctor" reveals repeated "4.130 NO [SERVERBUG] AUTHENTICATE Server error - Please try again later" for no good reason. (To invoke Connection Doctor, click "Account error" or "Account offline" button on upper-right corner in Mail, then "Open Connection Doctor", click "Show Details" to view errors.)

After finally adding account back without selecting "AOL", I noticed a significant difference from setting up via AOL: With AOL, IMAP offers four services: mail, contacts, calendars, and notes. With plain AIM, IMAP only offers mail and notes. (I never used AIM calendar, and stopped using AIM contacts since Mozilla Mail died.)

Since then, my AIM account hasn't been offline.

It is still strange that the same server, imap.aol.com (AIM account uses this server, too) gives different results. It could be some information that MacOS is not sending correctly. It could be that my AIM account (converted from Netscape, not a proper AOL "member") won't work with AOL setup. Or it could that [SERVERBUG] is just that, a server bug. Whatever the cause, I am sure this is affecting a lot of Mac users. I implore the two companies to work together to get this fixed.

[Image Edited by Moderator to Remove Personal Information]