Abstract: An envelope assembly for manufacture as a prestuffed, continuous form comprises two outer panels, a partition panel and an envelope flap on one of the panels. The panels having matching, glued together pin hole feed strips along sides, between which the flap extends, and line perforations for the removal of the pin hole feed strips. The partition panel is sealed along all four sides to one of the outer panels to provide a sealed, prestuffable compartment which may be opened by tear line perforations adjacent one pin hole feed strip, and has a glue line on the other side so that the compartment on the other side remains sealed when the sealed, prestuffable compartment is opened. The envelope assembly may be used as a certified mail assembly in which case the sealed compartment is used to contain a proof-of-delivery panel, for return to the mailer, which is removed with a portion of an outer panel for retention by the Post Office, while the remainder is handed to the addressee.