I got my mother in law to stop sending e-mails like that by telling her that they were really ID theft attempts. When you can't reason with them, fsck with them.
As a side note, my firm has a two paragraph disclaimer about legal privilege, federal laws, etc. due to the work we do. For a while I had 'Forward this disclaimer to 12 people in the next 4 seconds or you will have horribly explosive diarrhea for a year' in the monstrosity that had to follow every e-mail. Granted, the only people I e-mailed were my co-workers and occasionally a contact at a title insurance company that plotted with me to do this. No one ever mentioned it, but my boss caught it when re-evaluating the statement and made me change it. 🙁
********NOTICE*********
The information contained in this electronic message is legally privileged and confidential under applicable law and the information may be protected from disclosure under the Attorney-Client Privilege and/or the Attorney Work Product Privilege. This electronic message is intended only for the use of the individual or entity named above. If the recipient of this message is not the above-named intended recipient, you are hereby notified that any dissemination, copy or disclosure of this communication is strictly prohibited and may carry criminal and/or civil liabilities for unauthorized disclosure, dissemination or copying. Forward this disclaimer to 12 people in the next 4 seconds or you will have horribly explosive diarrhea for a year. If you have received this communication in error, please notify Attorney Dewey Cheatham immediately. E-mail is covered by the Electronic Communications Privacy Act, 18 USC §§ 2510-2521 and is legally privileged. Thank you.