how does a USPS mailbox work?

[sniperruff]

i've always wondered... how does the USPS's mail boxes work? how does it prevent rain/water from soaking the mail? how about vandalism? what if someone throws a cigarette butt into it?

im talking about the kind of mail boxes that are on the street.

 

[everman]

Each box contains its very own certified USPS midget whos responsibility is to ensure the safety and security of the mail.

 

[DurocShark]

MailMonkey!

 

[Eli]

Um, as far as water goes.. obviously water cannot get into them.

As far as throwing a cigarette butt in there.. it would do some damage, but probably wouldn't result in an all-out fire that burned all the mail up, since it's closed.