There were no consequences when this happened in the Clinton/Gore administration.

For example:

"The White House recently announced that all of Gore's e-mails from March 1998 to April 1999 are lost and unrecoverable because they were not recorded by the back-up tapes."

http://archives.cnn.com/2000/ALLPOLITICS/stories/07/11/white.house...e.mail/index.html