Due to an increased network threat condition, the Defense Department is blocking all HTML-based e-mail messages and has banned the use of Outlook Web Access e-mail applications, according to a spokesman for the Joint Task Force for Global Network Operations.

An internal message available on the Internet from the Defense Security Service (DSS) states that JTF-GNO raised the network threat condition from Information Condition 5, which indicates normal operating conditions, to Infocon 4 "in the face of continuing and sophisticated threats" against Defense Department networks.

The JTF-GNO mandated use of plain text e-mail because HTML messages pose a threat to DOD because HTML text can be infected with spyware and, in some cases, executable code that could enable intruders to gain access to DOD networks, the JTF-GNO spokesman said.