Abstract: A method for forming individual letters provided with envelopes from printed same-size sheets, includes pre-printed envelope forms for forming the envelopes, and in the immediate vicinity of each envelope form one or more letter forms for forming a letter or letters and inserting them in the envelope. The envelope form is led as such to envelope formation; the letter forms are cut at least on one side into letters which are smaller than the letter forms; the letters are brought to contact with the envelope form; the envelope form is folded in two around the letters and glued at the side edges to form an open envelope; and the open flap of the envelope is glued and folded so that a sealed letter provided with an envelope is formed.

Abstract: A method for folding and glueing a sheet of paper that contains informations and serves both as a letter and an envelope, wherein the sheet (40) is folded transverse to its parallel lateral edges (41). The lateral edges (41), the end edge (45) of the last folded sheet portion (40a) and the transverse edge (46) are closed by glue joints, and the folded and glued lateral edges (41) and the transverse edge (46) are perforated. The travel direction of the sheet is changed by about 90.degree. after treatment of the lateral edges (41). To make the transverse glue joints tight, transverse glueing of the end edge (45) of the last folded sheet portion (40a) and the transverse edge (46) is performed just before perforation of these parts by opening slightly the sheet portions (40a, 40b, 40c) that are to be glued together and by spraying glue on the slots.