I keep getting the same one from a certain car dealership every few months. Apparently handwritten address on envelope, real ordinary first-class postage stamp (even placed at a slight angle, so it doesn't look like a machine did it). Postmarked from a different state than the dealership is in. No return address.

Open it up though, and the deception ends immediately. Just your usual tacky, glossy printed brochure.

You should make Rick Astley postcards, and send them back to them the same way.