Came across this exact error the other day and didn’t know how to resolve it quickly nor did I have time to research it right then.
It happened when I opened Outlook, with a newly configured email account. Clicking on “Yes” made it disappear and that was the work around.
Basically to fix the issue, update the account settings with the new server name. As per MSOutlook.info, just click on the “View Certificate…” button and look at the“Issued to” name. This is usually the name that you’ll need to specify for your incoming and/or outgoing server in your account configuration.
Now, if I can only remember which Outlook had this issue…