Be sure to tell the op what you liked and disliked about his show. What pirates hate most is the listener who tries to suck up to them praising the program. Be honest and constructive in your comments. Tell the station about yourself, your equipment, hobbies, etc. Most pirates don't receive more than 10 or so reports per month, so each letter is an encouragement to continue his operations.
Mail is positive feedback to pirates.
Anyway, I think you'll be happy with your results. Dr. Napalm was playing classic rock from the Woodstock album. This station uses the Merlin, Ontario maildrop. A good selection of Elvis Costello tunes were heard. They were playing a collage of audio clips from various pirates, such as WRX, WHYP and Radio Bingo.