Hi @Meon Deking ,
Welcome to our forum!
Does this issue occur with all received emails?
And does this issue occur recently? If so, have you done any specific operations before that?
As i know, when you enable the "Read all standard mail in plain text" option, the issue will occur. Please check and confirm the option is not selected via File>Options>Trust Center>Trust Center Settings>Email Security:
Hope to help you!
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