Using classic Outlook for Windows in business environments
Hi Donald,
Since you're using Classic Outlook, go to File > Options > General. Under Personalize your copy of Microsoft Office, you can change the Office Theme to adjust the overall appearance.
If Outlook is automatically changing the background color of messages and you'd prefer it not to, select the Never change the message background color option. This will keep message backgrounds consistent regardless of the theme you choose.
I hope this helps clarify the issue.
If you're using New Outlook, or if you have any additional questions or need further assistance, please feel free to leave a comment on this post, and I'll be happy to help further.
If the answer is helpful, please click 'Yes' and kindly upvote it.
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