A neat trick would be to overwrite the original details (such as email subject) with something like "Did you really think you could unblur this?" in an identica

A neat trick would be to overwrite the original details (such as email subject) with something like "Did you really think you could unblur this?" in an identical font. With a security company, whose followers probably enjoy puzzles, you could go a step further and make a game out of it. For example, the unblurred text could contain a URL for a microsite that has a little game related to one of their products. It'd be fun and promotional at the same time. The downside is that this trains people to always try unblurring your blurred text and almost guarantees someone will find the one instance where somebody forgets to blur something.