How do I switch off the AutoComplete feature that fills in entries for the To: CC: and BCC: fields?
To turn off this feature, so that addresses are never suggested, go to Tools, choose Options, then click the E-Mail Options button, and then the Advanced E-mail Options button. Uncheck the box for Suggest names while completing the To, Cc and Bcc fields. If you want to remove an address from the displayed list so that it won’t be suggested again, open a new message and begin typing in the address. Use the up and down arrow keys to select the address to be removed from the addresses suggested. When the address to be removed is highlighted, hit the Delete key. To remove all the saved addresses, delete the .nk2 file where Outlook stores them.