The emails had been run through private accounts controlled by the Republican National Committee and were only supposed to be used for dealing with non-administration political campaign work to avoid violating ethics laws. Yet congressional investigators already had evidence private emails had been used for government business, including to discuss the firing of one of the U.S. attorneys. The RNC accounts were used by 22 White House staffers, including then-Deputy Chief of Staff Karl Rove, who reportedly used his RNC email for 95 percent of his communications.

If they are missing how would you know whether or not emails were classified? Couldn't it be that the general public were less computer savvy in 2007? Maybe it didn't get the attention because the subject of security and the implications were more obscure at the time. What's your expert, inside information, gut instinct tell you.