How to Clear Outlook Auto Complete Cache on Windows

If someone is getting an undeliverable message when sending to a known good email address, this is the fix.

Before you get started, you'll need to save all of your work and close Outlook completely. You won't be able to clear Outlook's auto complete cache if Outlook is open on your computer.

1. On your keyboard, press the "Windows" key (the key labeled with the Windows logo) and the "R" key at the same time. This will open the "Run" function.

2. In the Run pop-up window, click on the field next to "Open:" and type the following line of text:

Outlook.exe /CleanAutoCompleteCache

3. Once you have finished typing, click "OK."

4. Outlook will now open and the auto complete cache will be cleared.

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Creation date: 1/4/2021 10:04 AM (ejcourey@southern.edu) Updated: 6/6/2022 8:27 AM (lpangemanan@southern.edu)