I have checked the account settings. Because Thunderbird stopped working I started using Blue Mail and it has the same account settings. When I check for new messages I get this error message Sending of password for user ... @att.net did not succeed. Mail server inbound.att.net responded: Server error - Please try again later. It does not matter if my VPN is on or not. I have restarted the computer many times and I try Thunderbird after the restart and I get the same error message. I have double checked with ATT and my server settings are correct.