An envelope that allows a mailer to partly seal an envelop such that the primary content is sealed within the envelope while still allowing a third party to insert secondary material into the envelope is provided. An envelope includes a first sheet and a second sheet that forms a first pouch between the second sheet and the first sheet. The first pouch has a top opening and a side opening. The envelope also includes a third sheet that forms a second pouch between the third sheet and the second sheet. The second pouch has a top opening. The envelope also has a first flap for closing both the top opening of the first pouch and the top opening of the second pouch. The envelope also includes a second flap for closing the side opening of the first pouch.