When you move and mail is forwarded it creates a public record with the postal service. This is tracked by a large number of private companies specializing in p

When you move and mail is forwarded it creates a public record with the postal service. This is tracked by a large number of private companies specializing in personal information, including credit agencies, kept in databases forever. The databases keep track of everyone receiving mail at a given address during a given time. Even if you don't file mail forwarding orders formally, if you change your address with a magazine company or have a final bill sent, the company you do it with registers that information with the tracking agencies. There are rather comprehensive records of who you are, who you are related to, where they are now, and where you are now. Also tied into credit records, and multiple databases of public information including property purchases, property tax records, corporate incorporation documents, SEC filings, lost property and refunds claims in various states, etc. Most of the basic information is publicly available for free through any of a number of sites, with more detailed records including email addresses, phone numbers, birth dates, and identification numbers useful for credit lookups, available for a modest fee to anyone with a credit card who is willing to pay the fee, or any of their subscribers who pay for complete access. Obviously UPS subscribes to one or more of these services, it would be strange if they didn't.