A while back on HN, there was an article about private mail filtering services. You would have your ground mail sent to them, they would get rid of the junk mai

A while back on HN, there was an article about private mail filtering services. You would have your ground mail sent to them, they would get rid of the junk mail and send you only the "good stuff" that you specified. (Anecdotal) Well, these guys had a meeting with Postal Inspector who didn't think much of what they were doing. When informed that it was a voluntary service, he pretty bluntly informed them that it would upset the 400 or so of his (the Postal Inspector's) largest customers. Upshot, the Postal Service has a vested interested in you receiving junk mail because they are paid to deliver it, and woe betide anyone who interrupts that.