AIM mail suddenly wont send email

I have AIM mail configured in my mail.app to work through IMAP. Today and yesterday though, it just decided it wouldn't work any more. It comes up with

The sender *myemail* was rejected by the server smtp.aol.com.

Select a different outgoing mail server from the list below or click Try Later to leave the message in your Outbox until it can be sent.

So I try the other server which is smtp.aim.com and that isn't working either.

I've uninstalled and reinstalled the accounts, but no joy.

Even MobileMe, Apples own system has 'off days' Before changing a heap of stuff, try and find if there is a current AIM issue. Know anyone else using the same service - are they having same problems?