What is email address auto complete?
When an email address is configured in Microsoft Outlook, All the email addresses from the composed emails will be stored in .NK2 (Auto Complete List File). When you compose the email to same recipient again, the email address will automatically appear by typing few initial characters in the email address.
Where it is located in the computer?
Drive:\Documents and Settings\Username\Application Data\Microsoft\Outlook
Windows Vista and later versions
Why should i back it up?
When you migrate to a new computer or move the outlook to another computer, you need .NK2 file to have your auto complete list to appear
How to backup .NK2 file?
Go to the file location select the file copy and paste it in your backup media
How to restore .Nk2 file?
You need the file only when you change your computer or move the outlook to a new computer. Once outlook is configured in the new computer, copy and paste the .NK2 file from the backup media into its location