Microsoft Outlooks maintains a list for automatic completion of email addresses in email messages.  This list is automatically generated as one uses Outlook.  In some cases, such as the removal of a mailbox or a server migration, some auto complete entries may become out-of-date and prevent an email from arriving at the proper destination.  To remove these entries, please refer to the directions below:

Note:  This auto complete list can become corrupted.  It can be lost if the workstation's hard drive crashes.  Important contacts should always be added to the Contacts list.  Do not rely on the auto complete list as the only record for a recipient's name or email address.

How to remove individual auto complete entries:

Outlook 2010

1. Open a new email message.
2. Begin to type the email address.
3. When the desired entry appears, move your mouse pointer over it.
4. When the X icon appears, click it to remove the entry.

Outlook 2007

1. Open a new email message.
2. Begin to type the email address.
3. When the desired entry appears, use the up and down arrows on the keyboard to select it.
4. Press the Delete key on the keyboard to remove the entry.

How to remove all auto complete entries:

Outlook 2010

1. With Outlook open, click File and then Options.
2. Click the Mail tab.
3. Under Send Messages, click Empty Auto-Complete List.

Outlook 2007

Windows 7 or Vista:

1. Exit Outlook.
2. Browse to C:\Users\<username>\AppData\Roaming\Microsoft\Outlook\ where <username> is the username of the currently logged in user.
3. Append .old to files with the .nk2 extension.
   1.  If you can’t see the extensions, click Tools > Folder options.  Click the View tab, and uncheck Hide extensions for known file types.  Click OK.
      1. If you can’t see the menu bar (File, Edit, etc.), press the Alt key on your keyboard.