Abstract: A remailable envelope having an envelope body formed of front and rear panels, a first closure flap on the front panel and a return closure flap on the rear panel which is folded upon itself and inserted into the envelope body during the first mailing of the envelope. A perforated line divides the front panel into upper and lower panel portions, address information for the first mailing being exhibited by the lower panel portion. The upper panel portion is detachable at the perforated line by the addressee to expose the second closure flap for its expeditious removal from the envelope pocket. The second closure flap is large enough to substantially cover the lower panel portion during remailing and exhibits the address of the second addressee. The detachable upper panel portion can have advertising imprinted thereon or form a response document such as an order form for use by the addressee in return mailing to the sender.