Hi thee John and welcome
Is this in a corporate environment where everyone is using outlook 2013 or 2016? Or your just sending to friends?
ok, it is not possible sorry as it is controlled by the email program not the email itself.
In a corporate environment that is centrally based you can make an outlook for for it but in your case you cannot sorry,
If you would like any additional information or assistance, please do not hesitate to let me know.
Else if you can take a second to rate my service by clicking one of the stars at the top of the screen then submit, that would be greatly appreciated.