My question is two-fold.
First, do I address Save the Dates formally (Mr. and Mrs. John Doe) or informally (Jane and John Doe) or some other combination I am not thinking of? Our Save The Dates are a single photo front with a postcard back.
Second, since it's a postcard, should I still put a return address on it? Since this is our first mailing to guests, I would like to receive the return mail in case our addresses are bad, but I have never seen a postcard with a return label.
I forgot, I have a third item. Can we use clear address labels for the STDs, or do they follow the same "rules" as invitations, which I know it's not proper to use labels for?