A system for handling mail is in the form of a modular facility (10), which is capable of being isolated from the surrounding environment. The modular facility includes an enclosure or sorting area (40) for receiving and sorting incoming mail. A decontamination system (22) receives sorted mail and decontaminates the mail with a antimicrobial gas, such as ethylene oxide. A clean room (32), isolated from the enclosure and spaced from the enclosure by the decontamination system, is used for receiving processed mail from the decontamination system and sorting the mail for distribution. A source (92) of a decontaminant gas, such as vapor hydrogen peroxide, is fluidly connected with the enclosure for supplying the decontaminant gas to the enclosure in the event that the sorting room is contaminated or suspected of being contaminated with a pathogenic biological or chemical agent.