How do I clear the Outlook Auto-Complete Cache?

To clear the auto complete cache in Outlook follow the below steps:

Outlook 2010

Method 1

1. Open Outlook 2010.
   
2. On the File tab, click Options.
   
3. Click the Mail tab.
   
4. Under Send Messages, click Empty Auto-Complete List.
   
5. Click Yes.
   

Outlook will generate a new nickname cache.

Outlook 2002 through Outlook 2007

1. Exit Outlook.
   
2. Click Start, and then click Computer.
   
3. Click Organize, and then click Folder and search options.
   
4. On the View tab, click Show hidden files, folders, and drives.
   
5. Click OK.
   
6. Click Start, click All Programs, click Accessories, and then click Run.
   
7. In the Run dialog box, type the following command (including the quotation marks), and then click OK:
   
8. “C:\ Users\UserName\AppData\Roaming\Microsoft\Outlook” **Note Username in this path is the name of the currently logged on Windows user**
   
9. Right-click the .NK2 file that has name of the profile that you want to reset, and then click Rename.
   
10. Rename the file as profilename.bak, and then press Enter.
    
11. Start Outlook.
    

Outlook will generate a new nickname cache.

Windows XP

1. Exit Outlook.
   
2. Click Start, and then click Search.
   
3. In the Search Companion panel on the left, click All files or folders.
   
4. In the All or part of the file name: box, type *.NK2.
   
5. In the Look In box, click to select your local hard disk.
   
6. Click More advanced options, and then click to select the Search hidden files and folders check box.
   
7. Click Search.
   
8. Right-click the .NK2 file that has the name of the profile that you want to reset, and then click Rename.
   
9. Rename the file to profilename.bak, and then press Enter.
   
10. Close Windows Explorer.
    
11. Restart Outlook.
    

Outlook will generate a new nickname cache.