By default, when you type the first few characters of a contact name or an email address in the To, Cc, or Bcc field, your BlackBerry device displays the email addresses of recent contacts who are not in your contact list. To change this setting, proceed as follows:
1. On the Home screen, click the Messages icon.
2. Press the key > Options > Message Display and Actions.
3. Clear the Show Recent Contacts or Unclear or Uncheck the Display When Composing Email checkbox.
4. Press the key > Save.