A lot of people in Marburg have post office boxes. The mail delivery is somewhat sketchy, particularly if you don't have town delivery and are dependent on a rural mail service. Sometimes I think people also have post boxes so that they can catch up with the latest news and gossip and see who's doing what in town. If you don't frequent the pub, it's one of the only other options for socialising now that there isn't the thriving town centre of yesteryear.
Australia Post now offers a new service that notifies you via SMS, for a price, that you have mail waiting in your mailbox. Marburg doesn't offer this service. People aren't keen on spending the extra money. Besides which, if there's anything urgent, the postmistress can tell her sister, who can tell me when we both pick up our kids from school and I can stop in town on the way through.
If you're not home when a courier delivery comes, they'll drop it at the post office and our pre-SMS system will spring into action. Result, efficiently delivered packages.
It works just fine, it doesn't go down in a thunderstorm and the only price is privacy. Use heavy brown paper if you plan to send me anything interesting. Of course, that might start rumours of another sort entirely. It's best not to have anything to hide.