2. The method of claim 1 wherein the header properties are simple mail transfer protocol (SMTP) x-header properties.
4. The method of claim 2 further comprising adding visual markings to the message form selected from one or more security classification characteristics within the group comprising: inserting a classification identifier into a subject line of the message; inserting a classification identifier into a body of the message text; inserting a watermark in the body of the message form; and inserting security classification identification text at the start or end of the message form.