Abstract: Systems and methods of forming a mailpiece by folding an envelope sheet around one or more insert sheets (e.g., an insert stack) include creating the insert stack, staging the insert stack proximate to the transport path of the envelope sheet, dispensing the insert stack onto the envelope sheet, applying adhesive to the envelope sheet, using a buckle folder to wrap the envelope sheet at least partially around the insert stack to form an unsealed envelope without stopping the envelope sheet and without bending the insert stack, folding the envelope flap of the unsealed envelope onto the back thereof using a plow folder, and sealing the flap of the envelope to the back of the envelope, creating the mailpiece.