Here are some Jen's fan mails,which you can try: 1) Jennifer Capriati,
c/o WTA Tour,
133 First St., NE, ST. Petersburg,
2) Jennifer Capriati,
c/o Caroline Smith,
Office Manager (WTA London),
London, SW15 5XZ.
You can visit my site: www.jencapriati.narod.ru/Fan_Mail.htm for more addresses. Unfortunately, I didn't receive an answer from any of them, but I heard, that somebody wrote to the second address and has got an answer from Jen's managers. So, you can try.
Best of luck,