While it may seem incredibly trivial to some, I am often discouraged by the Send/Receive Mail setup. The only thing that really bugs me is the fact that I cannot mass delete previous mail. After a night and a day of selling items on the exchange and receiving fleet or player e-mails, it racks up fast with no efficient way to rid myself of the overwhelming amount of mail. If I could simply click a button that would delete all read mail, that would be the most convenient. That way nobody misses picking up returned/lost auction items, etc. but can still quickly be rid of the multitude of junk.
Just a suggestion, Cryptic, but I think it would go a long way to improve the little things. Remember, the big things will hurt the game, but the little things will kill it.