I think it's a little strange that submissions just sit in your inbox for forever unless you reject every one of them. This isn't meant as some sort of brag or flex, but I get a LOT of submissions when I open, and I don't want to have to individually reject 100+ submissions and send them a copy-paste rejection message rather than just accepting the 10-15 that I want, then the rest of them just expire after 30 days. 
It could also include an "on hold" feature, where the commission isn't necessarily accepted but it's also not rejected either, and it doesn't expire. So just in case you wanted to hold onto it for next time and your accepted slots are full, it's still there so the commissioner doesn't have to write it again.