E-Mail Disclosure Agreements?

sloondogger asks: "I got an e-mail from a customer the other day that included this at the end of what was a clueless and annoying attempt to communicate anyway: 'This e-mail and any attachments are confidential and may contain commercially sensitive information and/or copyright material of Southern Ocean Systems Pty Ltd or third parties. You should only re-transmit or distribute the material if you are authorised to do so. This notice should not be removed.' I don't believe that there is anything that is legally binding to this statement. I, of course, removed it when I replied. I thought it would be interesting to find out if these do have any sort of legal power at all or if they are just annoying wastes of bandwidth." Does such an agreement have any more weight now that electronic signatures have passed?