Updated: Apr 7
There is an entire system developed around mail delivery. There are codes to let you know where the mail should go aka zip codes. They are zipped because you have to “open” it. There are requirements to send mail such as postage- the sender or the receiver can provide the postage, it just depends on what type of mail it is. Receipants of the mail, use boxes to receive their mail like a PO Box or mailbox .