Outbound e-mail continues to be a big source of liability for employers, not to mention the legal headaches that message boards and blogs are causing, according to a new survey of more than 300 U.S. corporations.

In its fifth annual study of outbound e-mail and data loss prevention issues, Proofpoint, Inc., an e-mail security and data loss prevention company, found a number of legal threats that arise from corporate communications. The study, released last week, found that companies are battling information leaks from outbound e-mail, as well as newer communications media such as blogs, message boards, media sharing sites and mobile devices.