I just got a paper letter from Domain Registry of America telling me my domain was going to expire soon and I could renew with them for their best price. But they sent it to my home address, not the P.O.Box address I use for all domain contacts.
I don't know how they do this. I'm pretty sure I never used the address for any of my domains. The domain is actually my name (first and last) dot org. I haven't received any other letters like this for my other domains, so I think they have purchased a usps mailing list from someone and correlated it to domain names.
The letter in question was a pretty straightforward attempt to catch me sleeping. It stated my domain was about to expire, and I really really really needed to renew it, and by sending in 3 times the annual amount I currently pay they would be happy to transfer me to their service.