The long, strange journey of a Netflix DVD.

When you place a disc into the Netflix-provided return envelope, it’s addressed to a simple post office box number. So does Netflix have a gigantic P.O. box at every post office in North America? Nope—that box number written on the envelope doesn’t really exist.

The massive volume of DVDs being returned to Netflix would not fit in even the largest box offered by local post offices. Instead, the P.O. box number that Netflix rents at your post office is actually a huge sorting bin. (In the mail order industry, the term for this is “phantom post office box.”) Postal employees toss any returning Netflix movies into that bin throughout the working day.

Next, that full Netflix bin has to get to the closest of Netflix’s 58 distribution centers. That’s where the DVDs originate and to where they are returned. Generally, they’re anonymous, unmarked warehouses. That distribution center sends out to its service area each night—in the middle of the night—anonymous, unmarked white trucks to collect those bins from its area’s post offices. The trucks are due back at the distribution center before dawn, where employees tear open all those DVD envelopes, scan them as returned, and go about sending out the next item on your Netflix queue via the mail.

After more than a decade in existence, Netflix has the process down pat. That, and the phantom P.O. box system means that you don’t even have to use those pre-addressed red mailers. It certainly speeds things up, but if you ever lose your Netflix envelope, you can put the disc in a regular envelope, add a stamp, and write just “Netflix” on it, and it will get back to the distribution center. No address required—since you wouldn’t know what to write down.