I went to mail mine in the city where I work but the clerk did not like the way I folded the flap so wouldn't take it! I folded it past the line that was scored. I swear they all make up their own rules. I have mailed it like that dozens of times and there is nothing on the envelope that says "must fold here". I'm getting really tired of the postal system. I wish there was an alternative. Anyway, I came home and dropped it in the box at the post office so I don't have a tracking number. I've mailed them that way lots of times without a problem so we'll see.