that is an error from the server. So it could be something at their end and may be a temporary issue. I'm presuming you did all the necessary swapping to aol. One thing you could check: Suggest you check your Account Settings to make sure the 'User Name' is full email address. * Right click on mail account name in Folder pane and select 'Settings' * select 'Server settings' * 'User Name': make sure this is your full email address. check for typos and make sure there is no blank space at the start or at the end which is not so obvious. * Clear everything and retype email address. * click on OK * Close Thunderbird and wait a few moments for background processes to complete. * Then restart Thunderbird.