United States Patent # 5,819,241
"More particularly, the invention
relates to an interactive process in which a database of demographic and other relevant information is used to selectively apply specific, targeted information, such as advertisements, coupons, or messages onto a letter or parcel, if there is a match between the sender and/or recipient information on the letter or parcel and the information in the database. The database is constantly updated as letters or parcels pass through the system." This has privacy violation written all over it. Consider the implications of a database that knows everyone you've written to or received a letter from.
Jared Spool
"Now it doesn't matter if the actually thing that they are looking for is one click away or six clicks away, as long as they are able to follow the scent to get to the content, they will be very happy users. And the good sites get users to follow the scent."