Abstract: A return mailer is provided in which the outgoing and reply addresses cannot be confused, and the mailer can be changed over from an outgoing mailer to a reply mailer with a minimum of effort. The mailer includes a number of plies including a first ply having an outgoing address visible on it, at least one insert ply, a second ply, and a third ply. A sealing agent, such as tape covered by a release sheet or rewettable glue, is associated with one of the plies for sealing the plies of a reply configuration together. The second ply has a reply address printed on its outer, second face, and a portion of it is pivotally mounted to fold over the first ply.