Dear devs, I've been playing the game for long and spent a nice amount on it, and hence the suggestion. Many have spent plenty of money on Joker Boxes and ended with their inboxes filled with stuff. Some stuff i've recently got was permanent though, despite i had no idea. So, please introduce the rent period of a weapon to be seen in the e-mails (retrospectively, i.e. in the old emails too), as I and many others suffer from lacking that.