This is a bit of an odd post for me, But recently I stopped receiving email through Thunderbird using my @me.com address.
It looks to me like Apple has changed something technical at there around witch forced Thunderbirds to keep telling me that my password was incorrect. If you have had the same problem recently delete your @me.com Email address out of Thunderbird or your third party Email client and re-add the email account.
I noticed this change the IMAP Address from;
Give it a go see what happens and I hope this helps someone!