How to turn on or turn off AutoComplete

For a specific situation, you can turn this feature off, temporarily or permanently. To turn on or turn off the AutoComplete feature, do the following:
1. On the File tab, click the Options button:

2. In the Outlook Options dialog box, on the Mail tab, under Send messages, check or uncheck the Use Auto-Complete List to suggest names when typing in the To, Cc, and Bcc lines option to turn AutoComplete on or off:
