I've seen discussions on The Knot about stamps for the RSVP; etiquette says you should always stamp the RSVPs so the recipient of the invitation is sure to mail it back. I totally disagree. I feel that if they really want to come, they will go through a little trouble to get a stamp and mail it back. I've seen so many weddings where money has been wasted on people who will mail back the RSVP and don't even show up. Providing them with a stamp makes it easy for them to put the RSVP in the mailbox and not even think about it. I think since the wedding is already quite expensive, and you're providing them free dinner, drinks, and entertainment; the least they can do is put a stamp on it.
Miss June Bride 2017