The White House is having trouble coming up with a credible explanation for the now infamous missing e-mails. According to a White House spokesman:

I guess the bottom line is that our policy at the White House was not clear enough for employees.

And what does the White House e-mail policy say?

"Federal law requires the preservation of electronic communications sent or received by White House staff," says the handbook that all staffers are given and expected to read and comply with. [...] As a result, personnel working on behalf of the EOP [Executive Office of the President] are expected to only use government-provided e-mail services for all official communication.

Law requires, sent or received, only use...sounds pretty clear to me.