I have well over a hundred pages of PM's, It's impractical for me to scroll back dozens if not hundreds of pages of PM's looking to see if I have ever corresponded with someone before.

A search function would be a fabulous tool. I know I also keep literally thousands of email on my computers server, just in case. lol I like the ability to find that one email I am looking for by using the various search functions, it would be great to be able to do the same with my PM's.