"The Department of Defense (DoD) has taken the step of blocking HTML-based email. They are also banning the use of Outlook Web Access email clients. The DoD is making this move because HTML messages can easily be infected with spyware and executable lines of code that enable hackers to access DoD networks, according to an article in Federal Computer Week by Bob Brewin . A spokesman for the Joint Task Force for Global Network Operations (JTF-GNO) claims that this is a response to an increased network threat
condition. The network threat condition has risen from Information Condition 5 to Information Condition 4 (also called Infocon 4). InfoCon 5 is normal operating conditions and Infocon 4 comes as a result of 'continuing and sophisticated threats' against DoD Networks. The change to Infocon 4 came in mid-November, after the Naval War College suffered devastating attacks that required their entire system be taken offline, but the JTF-GNO spokesman claims there is no connection."