Well - you could send ahead to one of his concert locations. Currently on tour in Europe.

http://www.concertgroove.com/concerts/bob-dylan.html

OR - You could send mail to his home address:

Dylan, Robert - 29400 Bluewater Road, Malibu, CA 90265

This address is confirmed through real estate records of the county recorder's office. Two consecutive APN numbers.

Sincerely,
Gargoyle

Generally, I do not open most Christmas cards until the late Spring - Birthday Cards almost never. You should make it truly unusual to catch attention - say with handcrafted paper (I like using the lint from the clothes drier - it is already evenly screened and only needs starch,drying, and pressing) - and caligraphy with goosequill pen and beetjuice ink.