Hi Treworga,
What's your account type? Exchange, POP or IMAP?
What's the detailed version of Outlook?
As far as I know, there was a known issue that after updating to Version 1906 Build 11727.20210, you find that emails in your POP3 accounts are now shown as Plain Text rather than HTML as expected.
However, this issue has been fixed in Version 1906 Build 16.0.11727.20230.
If this is the case for you, please install the updated build immediately click File > Office Account > Update Options > Update Now.
If this is not your case, there could be something wrong with account data file, please follow the steps in
this article to repair data files.
Any updates, please feel free to post back.
Regards,
Perry
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