.NICK File Extension
File TypeOutlook 2000 Nickname File
File format categories include Binary, Text, XML, and Zip. The format of this file type has not been determined.
What is a NICK file?
Stores a nickname for an Outlook user, which is linked to a complete user profile; enables a user to enter a string of characters and assign it as a nickname for an e-mail address.
Outlook 2000 and earlier uses NICK files. Outlook 2002 and later uses .NK2 files.