This may not have been sensitive content, but still any compromises to a sensitive site should be evaluated and prevented in the future.
Pentagon e-mail system hacked
http://www.computerworld.com/action/article.do?command=viewArticleBasic&articleId=9025442
http://www.defenselink.mil/transcripts/transcript.aspx?transcriptid=3996
QUOTE: A hacker infiltrated the e-mail system at the Pentagon, forcing Defense Department officials to take about 1,500 unclassified e-mail accounts offline this week.