The advent of the Internet and email has completely changed the way we communicate with other people. When before we would have pen pals and engage in stamp collecting (an offshoot of having pen-pals from abroad), today we send email and digital photos over the Internet. Which brings me to the question: Is the mailbox obsolete?
For some people it may be true. While occassional bills still find their way into my mail box they have web-based counterparts which I take care of directly from the online banking facility that my bank provides. For purposes of bills and bills payment, mailboxes may indeed be unncessesary in this day and age.
On the other hand, offices that still require hard copies both for their filing system and therefore from their clients or subscribers as well, the mail box is alive and well and still being stuffed. And I suppose, until the personal digital signature has been perfected to the point where identity theft is impossible, I think the mailbox will be around for the next few decades.