Yeah definitely let him know how misinformed he is. He probably won't even read it so yes a rally is also a good idea.
If not already in your town, how about setting up a medical cannabis awareness day?
Invite this sob to attend. Have it every year, right in front of city hall if you can.
Flood his email with the truth about cannabis, send him info in the mail.
Contact NORML, or other pro cannabis groups, and let them know about this idiot.
They might even help you set up a rally/awareness day.
This is the sort of opportunity that should be exploited to increase awareness. Even if it doesn't make a difference to the idiot in question he can't ignore it, and it will help the movement as a whole. Think of the big picture.
This guy is your excuse to act...Just be respectful and discreet.
