Hi everyone. New to the community but not to Thunderbird which I've enjoyed for many years. I have Thunderbird for Windows 91.13.0 (32-bit) on a Windows 10 computer. A strange issue is happening when sending out messages for new accounts set up in Thunderbird. For new accounts set up in Thunderbird, messages are not sent out. Instead, the following error message is displayed: ''Sending of the message failed. An error occurred while sending mail. The mail server responded: Authentication rejected. Please verify that your email address is correct in your account settings and try again.'' Here's the odd thing. E-mail accounts previously set up in Thunderbird using the same e-mail server work without any problems. I removed one of the accounts that was working and re-created it today and now experience the same error listed above. I have tried creating accounts without security and same issue. So to recap, on the same computer using the Windows version of Thunderbird 91.13.0 (32-bit) does not send out emails for accounts created today. Accounts on the same e-mail serve created before today send out e-mail. I have also tried on a different Windows computer which is using the 64-bit version of Thunderbird 91.13.0 and experience the same issue. Any and all help is appreciated. Thanks. Jeffrey