PR people need to read what they send out. Can you image a press release going out to inform the world, yet contains the following harsh warning to keep it quiet:
This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you are not the named addressee you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately by e-mail if you have received this e-mail by mistake and delete this e-mail from your system.
Yup. Pretty much every day, press releases are sent to me about which I cannot talk. Even when they are sent by firms also boasting they won "2011 Communikations Agency of the Year." Who I cannot name, because the information is confidential and intended solely for me.
Heh. The wording of the keep-it-quiet-Buddy threat is identical, no matter the source, meaning one person wrote it, and then hundreds of firms disseminated, distributed, and copied it.
Oops. Then there's the vexing delete-this-email problem. If the policy of your agency or firm is that all emails must be kept for X number of years for archival and legal reasons, then you cannot erase accidentally-received emails.
Finally. The warning is at the very bottom of the email, where people are unlikely to see it. In any case, I love it when I get emails not meant for me, especially ones that talk candidly about, oh, certain people. Happens a couple times a year. I read them and enjoy them even more than my daily dose of 'LOL Cats'.
Hint. Do not implement policies that cannot be enforced.