Our Seal and Send, all in one invitations feature a unique folding format, containing multiple flaps that folds into one sealed card, ready for mailing. No envelope is required to mail. That's correct, NO ENVELOPE REQUIRED! It is as simple as fold, seal and send. The seal and send wedding invitations include a perforated, detachable RSVP postcard for your guests to return. Once sealed the invitation can be mailed without envelopes for the price of a first class stamp.