When you attempt to retrieve mail in an account, Thunderbird sends the stored password to the server. If you receive a message that the password is wrong, Thunderbird cannot assist, as it has only the password you initially provided. You can access that password by going to settings>privacy&security, and clicking 'saved passwords' and then 'show passwords', but that password is not working. You may need to contact your email host for a new password.

My error. I had two requests in French and mixed up my reply. Please ignore my response. Check the account online first, as it may be that your email host is sending to junk, prior to being retrieved by Thunderbird.

Si vous n'avez pas bien communiquer en anglais, s'il vous plaît utiliser geckozone - http://forums.mozfr.org/viewforum.php?f=4