As an attorney I see these appended to email messages all of the time and I have often questioned their efficacy. I understand the concept that such a disclaimer may place a recipient on notice that he should not distribute the email.
Nevertheless, are you reducing the effect of the notice when you attach it to ever email that you send? When the same disclaimer is included in a email to (1) a colleague about setting up a court time, and (2) the same colleague discussing confidential settlement discussions, has the effect of that notice been reduced?
In effect, by placing this notice on all emails, do we render the notice worthless?
In my practice, I do not routinely include such a notice in emails. Instead, if I am sending an email containing sensitive, confidential, or privileged information, I will manually append such a notice–usually at the top rather than the bottom of the email.
Doing so also gives me the chance to think about whether I should be sending the information via email in the first place. Perhaps a telephone call or a personal meeting it the best way to discuss the information.