[Cisserro]

Once you have so many mails in your box the following message pops up,

Awakened Lands Mailbox
Keep the Awakened Lands Postoffice Efficient!
Seems as if you have quite a lot of mail. Perhaps you should clean out your mailbox every now and then to keep the postman from going postal!

I know someone who has 10k mails in there box and the postman still hasn't gone postal.

I think once you reach a certain amount, the postman should go postal on your AR$. Once you clean it out, he will stop.