The person forwarding your mail is helping an old address release you gradually.

Leaving a place is never as clean as the date on the lease. Letters keep arriving for months, addressed to a version of you that lived somewhere else, and someone at the other end is quietly redirecting them. That work is invisible, unpaid in any real sense, and it is what makes a move feel gradual rather than severed. Endings usually need this kind of overlap to be survivable.

Consider who is doing the forwarding in your own transitions right now. Thank them if you can, and do the same for whoever moved out before you.