I've been tempted to buy a rubber stamp with "return to sender" or "not at this address" or whatever. I don't relish the thought of spending money to deal with

I've been tempted to buy a rubber stamp with "return to sender" or "not at this address" or whatever. I don't relish the thought of spending money to deal with other people's problems, though. In any case after a few years I just toss their mail in the trash, junk or otherwise. If they don't care to file change of address forms then I don't care either. I don't think this is technically legal, though.