Using older versions of Outlook for Mac in business environments
Based on your description, Microsoft is aware and actively investigating this behavior.
Replying to or forwarding an email does not include the original message in the email body in legac…
You can try updating to Outlook for Mac version 16.110.1 in Current Channel (has been rolled out). Some users have reported that updating to this version resolved the issue on their side (You can see at: Outlook for Mac Bug – Original Message Not Included When Replying - Microsoft Q&A)
It may take some time before a new release is available to everyone. If you can only see 16.110 on Current Channel, you can change your Update Channel to Current Channel (Preview).
I hope this information helps and if you have any further questions, please feel free to ask via comment section!
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