The simplest way to contact Jessica, is to try asking her a question on her official website.

http://www.jessicasimpson.com/questions.html

If you have no luck, you can try writing to either of the following two addresses. Please note that the second address is a Fan Club. Be sure to read my guidelines for writing letters to celebrities here.

Jessica Simpson
c/o Top 40 Entertainment
156 West 56th Street, 5th floor
NYC, NY 10019
USA

Jessica Simpson Fan Club
5116 North Jupiter Road
Garland, TX 75044
USA