I can no longer see my "sent" messages, the last one was about a month ago, and I've sent quite a few since . They don't count towards my message limit either.
No big deal, just thought I'd bring it up, and to see if anyone else has this issue.
You have somehow DEselected keeping a copy of sent items.
It is under Edit Options> Private Messaging > Click "Save a copy of Sent...> Click SAVE CHANGES at bottom of page.