Include a pre-printed response card with an EMAIL saying something akin to "I may be making a big mistake here, but no thanks" along with ten other options.
For starters, my responses to queries are automated. If I wanted to cut and paste text from your email and send it back to you, I'd have more staff.
Next, "I may be making a big mistake" can be very funny, but it's the kind of humor that can backfire easily. All it did was annoy me.
I know how annoying it is not to get a response to your queries.
I know this better than you might suspect cause it happens on my side of the submissions desk as well (and makes me NUTS)
However, you can not solve the no-response thing with a response card in either a snail mail or an email query. Don't do it. It's tacky. Not as tacky as not responding, but I DO respond to ALL queries and I did to this one as well: form rejection.