And in another case, Sydney, Australia-based Westpac Banking Corp. in November 2005 sent out e-mails to financial analysts containing preliminary full-year profit results that it had blacked out. But the information was in fact retrievable by the recipients, Fantuzzi said.

Such incidents, though relatively rare, demonstrate the challenges organizations face when trying to prevent data leaks, said Pete Lindstrom, an analyst at Spire Security LLC in Malvern, Pa.

'What corporate America needs to be worried about is the bigger picture, which is how do you manage data throughout the enterprise,' Lindstrom said. And it's not just leaks via metadata or document redaction, but also via other means such as e-mails, file transfer protocol downloads and chat, he said.