.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 a 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.