DoD Goes Plaintext

FederalComputingWeek reports:

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.

According to the article, they are converting all email to plaintext only. I wonder how they are accomplishing that?
While I agree putting OWA directly on the Internet is foolish, I think there are secure ways of doing that. Further providing users easy access to OWA encourages them to use an arguably more secure method of access than using a thick VPN client which offers full access to the internal network.
Soon the security folks will have us back to using smoke signals and carrier pigeons. Think about the man-in-the-middle attacks possible then.