Email Disclaimer Enforceable?

If you’ve received email from an attorney in the last five years, you’ve probably seen some version of a boilerplate warning/disclaimer in the message footer, indicating that the message may be privileged (or in some cases, asserting that the message is privileged!) and telling the receiver to destroy and/or return all copies if they are not the proper recipient. In the last couple of years, almost everyone has also added a statement to the effect that this email does not contain illegal tax advice (or if it does contain such advice, you shouldn’t use it!) Cumulatively, I’m sure we’ve used gigabytes if not terabytes of bandwidth attaching this text to every email sent.

My question to the world: is anyone aware of such an email disclaimer ever being enforced or held enforceable?