Hi Don Willa,
Could we know whether outgoing messages stuck in Outbox or delivered failed?
What's your account type? Exchange, POP or IMAP?
Please first go to File > Account settings > Account Settings. Double click your account and choose More Settings. Under Outgoing Server tab, normally, we will select outgoing server use same settings as my incoming mail server.

Please also check the server settings under Advanced tab. For POP or IMAP account, you could refer to
this article.
If issue persists, please try starting Outlook in safe mode and see whether this issue continues. This helps eliminate if the problem is related to any third party add-ins. To do this, please exit Outlook, press Win key + R to open the Run command, type
outlook.exe /safe, press Enter.
Besides, we could also test this issue
in a new profile to check the result.
Any updates, please feel free to tell me.
Regards,
Perry
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