Abstract: Envelopes for certified mail each comprising a panel and a flap constituting an integral, one-piece assembly of thin card stock with a fold line between the panel and the flap. When the panel of the panel and flap assembly comprises the rear panel of an envelope a removable return receipt card is formed therein by lines of perforations and is preprinted on both sides. A Certified Mail endorsement and a return receipt request are preprinted on the flap. A paper front panel is adhered to the inside surface of the rear panel. When the panel of the panel and flap assembly comprises the front panel of an envelope a removable return receipt card is formed in the flap by lines of perforations and is preprinted on both sides. A Certified Mail endorsement and return receipt request are preprinted on the front panel. A paper rear panel is adhered to the inside surface of the front panel. In both embodiments, the envelopes may be assembled individually or in the form of a continuous strip thereof.