.NK2 File Extension
File TypeOutlook 2002 Nickname File
File format categories include Binary, Text, XML, and Zip. The format of this file type has not been determined.
What is an NK2 file?
Contains the nickname for an Outlook user that is a associated with a user profile; allows a user to create a nickname and assign the name to an e-mail address.
Outlook 2002 and later uses NK2 files. Previous versions of Outlook use .NICK files.