This question has been coming up a few times: Q: How do I empty the PM's in my message trash? Answer: We leave PMs in Trash indefinitely. However, once each night, we'll check to see if you have more than 20 Trashed PMs and delete the oldest ones after there are 20+. For example, if there are 25 PMs in your trash box, we'll delete the oldest 5 and will leave the remaining "newer" trashed messages in place. We may add a "delete trash" feature in the future, but it is a relatively low priority.