New clan mail system (to increase space)
Clan mail often doesn't have enough space to make the entire point the sender wishes to convey, but if the mails are given too much space they could fill up the inbox. As such, I would suggest that the inbox be set up like that of email. Each mail could have a subject, which the player would tap to access the mail, which would have a huge amount of space. Since the subject lines would take up very little space, the inbox could also hold more mails, and it would open up the ability to delete clan mails.
I actually already suggested this in another thread, but that thread was primarily about cooldown reduction, so this suggestion got lost in agreement and disagreement about the cooldown.