Send an Email to All Contacts in Outlook

To send a message to all your address book entries easily in Outlook, Outlook Express, or Windows Mail:

  1. Start with a new message.
  2. Click on To:.
  3. Highlight all your contacts on the left by following the next three steps.
  4. Click on the first contact.
  5. Hold down the Shift key.
  6. Click on the last contact.
  7. Click on Bcc: –›.
  8. Now click OK.
  9. Enter your email address in the To: field.
  10. Compose your message.
  11. Finally, click Send.

From http://email.about.com/cs/oetipstricks/qt/et020102.htm