E-Mail Has Permanence
Each E-Mail you send is more than likely saved or archived on your computer system or on the recipient's system; therefore, do not assume that an E-Mail message no longer exists, even if you delete what you received or sent. Your thoughts and interactions with others, via E-Mail, are archived and saved, potentially for posterity.
In financial services organizations, all data must be saved for a minimum of seven years. Think about what you are writing and what legacy you are leaving through such communications. E-Mail communications can be presented in a court of law.