Resetting the Nickname and Auto Complete Cache in Microsoft Outlook

Outlook maintains a nickname list that is used by both the automatic name checking and the automatic completion features. The nickname list is automatically generated as you use Outlook. If the nickname cache is corrupt Outlook may not be able to identify recipients, may offer incorrect recipients when automatically completing the email address, or may send the message to the wrong person.

Use the following steps to reset the Outlook nickname cache.

1. Close Outlook.
2. Open C:\Documents and Settings\<username>\Application Data\Microsoft\Outlook.
3. Search for File with extension *.NK2.
4. Right-click the .NK2 file with the name of the profile that you want to reset, and select "Rename".
5. Rename the file to
6. Restart Outlook.

Outlook will generate a new nickname cache.

Note:

If you try to locate a NK2 file with Start > Find on a Windows 2000 or XP system, please be aware that Windows treats these files as hidden files. In Windows Explorer, use Tools > Folder Options > View to make sure that hidden files and folders are shown. By default the folder "Application Data" is hidden by Windows.