I figured it out...
The DUmmy bravenak left enough info out on the intertubes to be tracked down. Searching her DU name 'Bravenak" via Google leads to her blog. Her blog provides her city and state, Google also links to her domain. Her domain registration provides her name. So, yeah, an internet stalker from Florida may very well have sent her these letters to harass her. Finding a street address with a valid name, city, and state is a piece of cake.
It took me all of five minutes to find out what the sender of the letters most likely did.