Where is my account storage being used?

Where is my account storage being used?

My account was recently blocked due to me being over my storage quota. I removed several sent items and messages in the trash and got my quota back below 100%, thus unblocking my account. The interesting thing is that even though my account is unlocked after deleting many of these messages it still reports that I am using 95% of my quota. I did leave a few messages in the inbox and in the sent items but it is reporting that each of those are only using 1%. Where is the other 93% being used and how can I gain back that storage quota?