A network security system is deployed between an internet backbone and intranets that belong to subscribing organizations. The system includes a scanning system that scans incoming electronic mail for malicious code and an anti-virus server for downloading anti-virus code to clients on the intranets. A switch is provided for directing incoming electronic mail from the internet backbone to the scanning system so that the electronic mail can be scanned. In one embodiment, a decoy server is also provided for masquerading as a legitimate server and logging suspicious activity from communications received from the internet backbone.