1. Start Macmail and double click on the suspected hoax message to open it as normal
    Opening up the email
  2. Click on the View button on the Toolbar, then hover the mouse over [Message], then click on [Long Headers] as below:

    Showing full headers option
  3. This will display the full headers. You can then highlight them and copy the text and paste it into a new email.

    Full headers button shown activated