Can you solve this direct mail mystery?

I’m not one to usually post about direct mail, but I received something so strange over the weekend that it’s time to dive way below the line and see if anyone can solve this little DM mystery. It came by way of a small manila envelope. For my address, it uses a typeface I’m sure most of you have seen before—one that looks, at first glance, handwritten. The envelope bore no return address and had a hard-to-make-out postmark—all I can tell definitively is that it’s from Illinois.