A mailer product is provided which is formed from a single sheet of paper having first, second and third sections. The first and second sections are separated by a first transverse line and the second and third sections are separated by a second transverse line. The sheet of paper is foldable along the first and second transverse lines so that the first section overlies the second section and the third section overlies the first and second sections. First adhesive material is provided on one of the first and the second sections of the sheet for securing the first and the second sections to one another when the sheet is folded along the first transverse line, thereby forming a return envelope. Second adhesive material is located on at least one of the first, second and third sections for securing the third section to at least one of the first and the second sections when the sheet is folded along the second transverse line, thereby forming a closed mailer. A method and apparatus is further provided for forming such a one-piece mailer.