A method, system and article for producing an envelope having improved seal integrity. The method comprises the steps of disposing at least one material at the interface of the adhesive seal between the flap and the body portion of the envelope, which material exhibits a characteristic property when combined with an activating agent. The envelope is then sealed by closing the flap onto the body portion of the envelope such that the activating agent combines with the material along the sealing interface. The sealing interface is inspected to determine whether the material exhibits the characteristic property thereby confirming that a seal has been produced between the flap and body portion of the envelope. The system and article are directed to the various modules of a mailpiece fabrication system employed to produce the mailpiece including an inspection module for confirming that a seal has been formed.