Do they trace every piece back to every sender? Of course not. However, it has been used multiple times to trace back to a sender (Postal Service Photographs Every Piece of Mail in the U.S., Shares With Agencies That Request It), so "actually" would apply as well. It seemed verbose at the time to write "track it back to the sender if needed", so I used "potentially" as a means of saving bandwidth. Apparently, I chose poorly.Potentially, not actually.