I totally agree. I will stay tuned if you get further on this.
This is all I've found:
https://vborg.vbsupport.ru/showthrea...rivate+Message
Promising since in the image it shows Delete then a Go button at the top of the message, but not "exactly" what we want.
Secondly
https://vborg.vbsupport.ru/showthrea...rivate+Message
Delete a message in your inbox after you reply to it, compatibility is a question since its from vb2.0 something.
We need Boofo or Marco, since they made similar or related hacks.