Canadian developers at Authentex Software are now shipping an antivirus product for Microsoft Exchange. The ThunderByte product detects polymorphic and macro viruses on email attachments before the documents are opened. The company said the tool integrates with the messaging engines running on Windows 95 and NT, then notifies both sender and receiver. Contaminated documents can be automatically deleted or "quarantined" in special files to be disinfected later. The product sells for $49.95.