I'm having the same issue...
So here is what I did to resolve... Not a pretty fix, but it works...
All i do everytimes this happens (at least 50% of teh times i start iChat) I just quit and restart ichat sevral times and it finally logs me in.
I'm sure there is a better solution, but for the lack of time I have to research this, as I realy on iChat on a day-to-day basis, this is what i have been doing. If anyone has a better or more permanent solution, PLEASE share!
Since 4 days ago, I have been receiving the same error message, and unlike "rich 295" logging in / out / quiting / reopening does nothing more than give me the same error message a few times then eventually "times me out" for attempting to log on too often. I would have thought this to be an acute incident on my personal home computer (iMac using 10.6.8) however my newer computer at work has same exact issue (sorry not sure of exact system at moment). I receive the message three times as it attempts to login (username)@mac.com, (username)@icloud.com and (username)@me.com all consequetively. How exactly was this fixed? I've looked up old threads suggesting to change ports, etc, but to not avail can I make any forward progress. This is frustrating as my work requires me to communicate online and frankly iChat is perfect for what I need. Any help would be great, thanks
I guess AOL is generally ending its support of those mac.com accounts in AIM by December 2013, interpreting this:
It does seem to be about mail in general.
In some ways AIM is somewhat separated from AOL in that you can register from an AIM Screen Name separate from an AOL one.
On the other hand the AIM Registration page used to allow you to list any other email as the AIM Screen Name (you could in fact register a Gmail ID as the AIM screen Name just to confuse things).
Some United States ISPs also have their email addresses allowed and AIM Screen Names.
The Notification does seem to list Apple Issued IDs and not just any iCloud linked Apple ID.
The process was that you could obviously have an @mac.com ID based on the paid for .Mac service and link this to an @me.com from MobileMe at the change over of those two services. Then when iCloud came out you could initially change it to an iCloud one and later Apple issued @iCloud.com IDs in addition for early iCloud adopters and now as standard.
However I have an external ID to Apple and have made that my iCloud ID.
It has given me an early @me.com and an @iCloud.com IDs as well.
Although it is convenient linking several IMAP services together does not seem to be that secure.
The agreement that Apple issued IDs would be recognised as AIM screen Names goes back to the start of iChat (version 1) in 2003. That's 10 years.
I had a quick look at the Google Settings and it only list being able to have other IMAP services pick up the mail and nothing about importing other services. (it was only a quick look)
I can see it might be a possible though that the agreement is coming to an end.
iMac 2.5Ghz 5i 2011 (Mavericks 10.9)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
Mac OS X (10.6.8),
Couple of iPhones and an iPad