That's a good idea! I like how it works that many postal workers and other mail handlers will see your message even if it is ignored by the addressee. Not expensive either. I might borrow this idea, I really like it!
Good thinking. I've read many times that a hand written note is the best way to get attention whether it be the press or politicians. It's also said that use of an envelope almost guarantees a note will be read as it will always be opened because it just might be a donation LOL.
Email is too easy to ignore.
I got a similar idea, from an Amnesty International site, to use postcards when I tried to contact people who could help Terri Schiavo.
As you said, when you send postcards, you are educating the people who handle the cards.
Also, there is no need for an assistant to delay opening the envelope out of fear that some toxic substance, like powdered anthrax, lurks in the envelope.