Outlook's AutoComplete list is an efficient tool. Better to be safe than sorry: Back up this file regularly.
- Close Outlook.
- Open Windows Explorer and enter the following address in the Address control: %appdata%\Microsoft\Outlook. Windows Explorer will update to the appropriate Outlook folder.
- Right-click the Outlook.nk2 file. It may have another name, but there should be only one file with the .nk2 extension.
- Select Copy from the resulting submenu. From there, you can copy the file to an external drive, USB drive, or CD — wherever you store your backup copies. If you copy the file to another folder on the same local drive, be sure to rename it to avoid problems.