To provide a sheet for an envelop which not only encloses a content but can print a lot of data thereon, which can be used for return mail, and which contributes to the decrease in waste and for saving resources eliminating a film window different from an ordinary mailing envelope.

(1) An oblong sheet is divided into a plurality of sections for its top end and bottom end to be used as two flaps, one for sealing and the other for address printing. (2) Using a pressing type or re-wetting type adhesive and lateral and vertical perforations, most of the inside area of the sheet (inside face of the envelope) is saved as a section for data printing, and the outside as a section for advertisement. (3) By folding and pressing, the sheet is formed into an envelope shape with the top flap open, and after a content is enclosed, the envelope is sealed with the flap. (4) When no content is needed, the top flap can be folded as the bottom flap is folded to be weakly pressed and sealed to be used as DM. (5) Depending on the type of adhesive chosen and how the perforation is made, it can also be designed to form a return envelope.