As we keep getting our Private Messages reduced and reduced, a problem alot of us have been running into, while PMing each other back and forth or trying to reach out to someone via PM, we have to go to a thread that they started to have the best chance that they receive an email stating someone responded to their thread when someone is just simply stating "Hey, clear out your Inbox."
Why do we not have a notification that pops up and states that your Inbox and Sent Box is full? This happens to me all the time whether its my inbox that gets full or the person I have been trying to reach gets full. Its so frustrating to try and track down that person to get them to clear out their PM's. I have lost deals with people exceeding their maximum PM limit. There are alot of people who have de-selected the option where anytime you post a comment in a thread, you are subscribed so trying to get ahold of that person is often times impossible. Its like you have to post in a thread like you do in Craigslist in the Missed Connections in hopes that person reads it.
Solution would be a pop up everytime you get onto the site, maybe time elapsed, or maybe an email once a day that cannot be turned off in your settings.