... as I said -- and forgive me because I am not awake yet -- if Private message notification gives you such a headache, change your options to receive them by e-mail. It's much, much faster to view them on your own machine than over the Internet.
Editing the subject line would make it nearly impossible for us to go through and delete those thousands of useless notifications from the system every once in a while as is necessary to keep the site running.
edit : I am trying to look into it, but the way Xoops 2 works, it appears at this moment to be virtually impossible to change the way notifications work without MAJOR modification. As will all crap Xoops, rather than simply call the text, it calls a file, which calls a subroutine, which calls the text, and at first glance -- remembering that I haven't had time to wake up yet -- there doesn't appear to be any way to pass the parameters necessary to alter the subject line per post.
Wayne