Clearing the Outlook Nickname Cache

The Nickname Cache is used by Outlook for automatic name checking and the automatic completion.

I you want to clear the cache with the list of names that Outlook shows when sending an e-mail

1. Close Outlook
2. Start the Windows Explorer
3. With the focus on the root of the C: drive, search for *.nick (Outlook2000) or *.NK2 (Outlook2002 or newer)
4. You will find a file that starts with your profile name
5. Rename this file
6. Restart Outlook
7. Outlook will start rebuilding the file over again.