Comment 36 for bug 297301

It's definitely not fixed as many gmail users will tell you.

While it may be difficult to grok the various and different server error messages, it is not impossible. There are less than 10 (major) IMAP servers in use today. Courier, UW, Exchange, Binc, Dovecot and gmail come to mind.

I can't understand how the behavior of forgetting the password helps protect the user from being "locked out" of an account, as the user, lacking any information as to why they are being asked for their password, is just going to enter the same "bad" password that they think is correct.

The pop-up doesn't mention any information like "Thunderbird has decided to forget your password because it thinks it's 'bad'. "