You may write Charles directly using the following mailing address:
Charles D. Watson B37999
480 Alta Road A5-201L
San Diego, CA 92179-0001
Charles is able to receive emails and photos on paper the same day or next, using the JPay email service. To set up an account, look him up by choosing "California" for the state, and "B37999" for the Inmate ID. Be sure to include your mailing address in your email if you desire a response he won't be able to reply by email until later this year.
He would love to hear from you. Thanks!