I wrote to Burning Man recently:
I ordered 2 Burning Man tickets. They recently arrived and it had an Atomic Fireball in the envelope. I love the sentiment, thank you!
It would be much appreciated if I had received one Fireball per ticket. That way, both my partner and I could have our Fireballs. Last year I ordered two tickets and received just one Fireball as well.. :-(
You spent the effort (and used that big envelope) to include a Fireball, having one per ticket is only right. :-)
Here was the response from Frog at Burning Man
Hi Lee. The secure mailing option as required by the post office says we need to have our envelopes 3/4 inch thick so your package can be signed for. We thought it would be fun to send something useful that keeps the envelope 3/4 inch thick for the post office requirements, but we found that if we sent more than one fireball the flap on the envelope has a tendency to come open and tickets have been stolen in the mail. So, as much as we want to make people happy by sending a piece of candy to each and every one of you, we would rather you have your tickets safe and sound.
I did a little digging and.. yup, the least expensive way to send a letter that requires signature confirmation at the receiving end is to make sure the letter is at least 3/4″ thick. That way you can call it “First Class Package” and get Signature Confirmation service for $2.20. Total price for a 3 oz letter is under $4. Otherwise, you’d have to use Priority Mail with Signature Confirmation for $7.15.
So it looks as though if you give USPS a letter that can’t be machine sorted, it’s less expensive than if it’s machine sortable. Hmm.