Usefull links
http://www.nk2.info/
• NK2.info is a small utility to view and export the contents of an Outlook auto completion file.
• NK2.info can recover e-mail addresses and names from a corrupted NK2 file!
• NK2.info is free
http://www.nirsoft.net/utils/outlook_nk2_autocomplete.html
This utility reads the AutoComplete file of Outlook (with .NK2 extension), displays all email records stored in it, and allows you to easily export these records into text/html/xml file.
It also has an experimental feature to import your outlook addressbook to the nk2 file
http://www.ingressor.com/about_nk2_files.htm
A full-featured NK2 (auto-complete) file editor. Commercial software, pricing starts at $40 to $350