I think there is a section for you to sign the M.O. in the lower right section, just like a check, which I would guess is hte Purshaser line. Put who is getting the money on the Pay to the Order of line. I think the recipient line is just like the notation part of a check-write something there if you want to so you can keep track of the transaction.

I always sign a money order and keep the carbon. I don't know if it's negotiable without the signature, but why not sign the dam thing? I also am unsure what would happen if you tried to submit a claim for a lost money order that was not signed.