Hi @86238006 ,
Welcome to our forum!
Agree with DillonJS, please kindly understand that since the support for Office 2010 ended on October 13, 2020, and there will be no extensions and extended security updates, you can still use your office programs. For your better user experience, it is recommended that you use a newer version of office.
And according to your description, i have done research and found a similar known issue as yours:
If that's exactly what your problem is, try the workaround mentioned in this official article. More information: Outlook error “Cannot send this item” when replying to an email.
In addition, i notice that after updating the Office, the issue gone away. Updating Office to the latest version in my opinion is the most effective solution, especially if you are more inclined to continue using Office 2010.
Hope the above help!
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