online education

In an interesting twist of fate, ever since I graduated with my Ph. D. in educational technology I have gotten a large number of snail mail letters imploring me to "finally complete my education so I can get ahead"  from institutions such as University of Phoenix and Argosy University. There's not too much farther one can go after a Ph. D. Even if one could, I am not so sure I would want to. I am wondering where this surge in such letters has come from. Did Purdue sell my address?