Abstract: The present invention is directed to an enclosure with a base and a movable lid. When the lid is open, a piece of potentially harmful mail can be placed within the enclosure. The enclosure may include at least one latch for sealing the lid to the base so that an air-tight chamber is formed within the closed enclosure. Preferably, the latch can be broken-away to secure the lid in the closed position and deter tampering with the enclosure. The enclosure may also include a self-sealing valve member for allowing a sample of air or particulate within the closed enclosure to be taken and tested. The enclosure may further include tools such as a letter opening instrument, a sampling instrument, and/or testing material.