Ever since the "New Outlook" was released, MSoft has been pushing for all users move to this new version. When I first tried it, I noticed that the New Outlook would not allow me to edit the subject line for any incoming emails. Therefore, I DID NOT switch over. Today I realized that even in the legacy Outlook, this feature is no longer available. MSoft makes us believe it's available, but after about a minute or so, the edits just vanish.
[snip]
Sorry. Bad advice. Withdrawn.
This has worked for me with every MS email program I've used in the last 25 years. Try it.
Make the outlook window smaller than the Desktop.
Drag the message from Outlook to the Desktop.
Open that message with Notepad or another text editor.
Edit the Subject and anything else you want to edit.
Save as EML.
Drag the message back into the Outlook folder you want it in.
You should now have 2 versions of the message, the original and the edited.
Don