How to Clear/Disable the Auto-Complete Cache in Outlook 2010

The transition from an internal Exchange server environment to a Hosted Exchange environment can often lead to an Active Directory battle. The Auto-Complete function of Outlook will still retain the old Active Directory entities, even though the email addresses appear correct or are newly entered.

In previous versions of Outlook, deleting or renaming the NK2 file would alleviate the issue. Within 2010, however, the file structure is much different. Fortunately, Microsoft has created a menu item to clear the file contents or disable the function.


1. In Outlook 2010, click the File menu.

2. Click Options.

3. From the Options menu, click Mail.

4. From the right window pane, scroll-down to the Send messages area. By default, the Auto-Complete check box is selected. Clear it to turn this feature off or click the Empty Auto-Complete button to clear the local cache.

5. Click the Yes button to confirm.

© 2016 AppRiver LLC.  All rights reserved.

Add Feedback