The internal "mail room" used to be a much bigger deal. At large companies, some number of times a day an actual person would come around with a cart, put thin

The internal "mail room" used to be a much bigger deal. At large companies, some number of times a day an actual person would come around with a cart, put things in your in-tray and remove things from your out-tray. Once their round had been completed they would return to the mail room to sort the outgoing materials and then repeat the process. I suspect that one of the reasons "starting in the mail room" used to be so venerated is that it's a good way to get to know a wide swath of people inside a company in a relatively short period.