I can write a greasemonkey script to mimick Gmail's "undo send" function by delaying the PM sending for 10 seconds; would that be in demand?
None.
Even just being able to delete the PM before the person sent it would be enough, if nothing else. That way you could just delete it and resend the edited version at your convenience.
We can't explain the universe, just describe it; and we don't know whether our theories are true, we just know they're not wrong. >Harald Lesch
Split into two folders: Outbox and Sent