Hi @cteljr ,
Could you clarify which type of email account you are using? Is it an IMAP or POP account?
Have you made any changes in STMP settings prior to the occurrence of this issue?
In order to help narrow down the problem, please try sending a message from the web mail and see if it can be sent successfully.
If there's no issue in web mail, I'd recommend following the steps below in order to troubleshoot further:
- Start Outlook in safe mode (Press Windows + R, type "outlook /safe", press Enter.). If it works fine in safe mode, chances are that the issue could be related to any add-in, then you can enable the add-ins one at a time to find out the culprit.
- Create a new Outlook profile, add the email account to it, switch to the new Outlook profile and check the result.
Overview of Outlook e-mail profile
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