Before you send out or forward any e-mail message, ask yourself if the contents of that message will become a boomerang for you or your company.
Subjects that are usually discussed in whispers at the office are best kept out of an e-mail.
Rumors, gossip, and other issues not directly related to the organization's business should be kept out of an e-mail.
Before you send out that e-mail, ask yourself "If this email were accidentally sent to everyone in the organization, would I be in some kind of trouble?"
When you send an e-mail to someone outside of the company, keep in mind that you represent the organization and not just yourself, and your company may be held responsible for your actions.
Remember: Any bussines or professional e-mail is a document with 100% of posibilities to be public. Be aware of this risk always.
Don't loose your time and money clarifiying messages. Pick up the phone or go face-to-face.