Brother is receiving mail at my address, but he never even knew my address.

Apologies if this doesn't belong here or if there is a better place to ask.

Around last month or so, I received a letter at my address that was addressed to my brother who lives in a different state **EDIT:** We're both in the U.S. (he used to live in this state, but I'm not sure if that is relevant). It was some local social justice nonprofit or something asking for donations/membership. He confirmed he never registered to anything like …

address justice letter live local mail privacy social social justice state