Abstract: An envelope is formed from continuous COPP film web by precreasing envelope body (13) and flap (14) fold lines along the web, continuously installing an adhesive tape along the flap portions and pre-cutting relief slots in the web corresponding to the flap side edges (15). The pre-creased web is folded and cut into individual envelopes by hot knife cutting, whereby the presence of the slots prevents the flaps from welding to the side seams even with the flap folded over. Envelopes produced by the method are suited to automatic stuffing. Apparatus for making envelopes in accordance with the invention is also described.