From MozillaZine Knowledge Base
- This article was written for Thunderbird but also applies to Mozilla Suite / SeaMonkey (though some menu sequences may differ).
If you have a Gmail IMAP account you may run into a "The server returned the error: Account exceeded bandwidth limits. (Failure)" error message on startup or if you try to copy/move a lot of messages. You might also get a "Login to server imap.gmail.com failed" error message , followed by a prompt for the password.
The same problem can occur with a Gmail POP account if you have a lot of new messages in your inbox and it tries to download all of them.
This is due to a limit imposed by Gmail on how much bandwidth you can use. If you wait 24 hours the lockout will be removed. However, as soon as you exceed the bandwidth limit again the server will lock you out again. This problem does not occur with just Thunderbird, though Thunderbird's default settings make it more likely to occur. Neither the limit or the error message are documented by Gmail, though there are plenty of threads in thier support forum about them.
- If you have a IMAP account consider temporarily disabling offline folders (uncheck Tools -> Account Settings -> Gmail -> Synchronization & Storage -> Keep messages for this account on the computer) and global search/indexing (Tools -> Options -> Advanced -> General -> Advanced configuration -> enable Global Search and Indexer) as they download copies of all of your messages in the background. As a minimum uncheck "All Mail" from the list of offline folders as it contains a copy of all of your messages for that account, essentially doubling the number of messages that get downloaded.
- Try exiting Thunderbird and filling out the unlock captcha form using your browser. Enter your username and password, then the letters that you see in the box below. Once that succeeds (it make take several tries if you have problems reading the letters in the captcha) log out of Gmail and try using Thunderbird again. If you are using Google Apps (rather than Gmail) use the captcha at "https://www.google.com/a/[domain.com]/UnlockCaptcha" instead. If your ISP provides a free Gmail account they use Google Apps to do that.
Gmail will temporarily disable your account if you send messages to more than 100 recipients or have a large number of undeliverable messages. That should cause a "550 5.4.5 Daily sending quota exceeded" or some sort of message bounced error rather than a account exceeded bandwidth limits error. The two errors are sometimes confused because both have a 24 hour timeout. Gmail may also close an account after 9 months of inactivity.