From NirSoft Freeware
Every time that you type an email address or name in the message window of MS-Outlook, it automatically offer you a list of users and email address that you can choose. This feature is known as 'AutoComplete' and Outlook automatically build this emails list according to user activity and save it into a file with .NK2 extension.
In some circumstances, you may need to fix or modify the values appeared in the AutoComplete list, or you may want to remove unwanted email addresses and/or to add new email addresses. MS-Outlook doesn't provide any ability to edit this AutoComplete list, so this is where NK2Edit software can help you.
* Easily modify or fix all information stored in the NK2 file, including the display name, the email address, the exchange string, the Drop-Down display name, and the search string.
* Easily remove unwanted single quote characters from the display name and from the Drop-Down list.
* Delete unwanted emails, as well as add new emails, by typing them manually, or by choosing them from the address book of Outlook.
* Copy NK2 records from one NK2 file to another - simply by copy and paste !
* Build a completely new NK2 file and add the desired emails into it, by typing them manually, by adding
* Added 'Duplicate' column, which allows you to easily find duplicate NK2 records with the same display name/email. Simply click the 'Duplicate' column header, and you'll find all duplicate records in the top of the NK2 records list.
* Also Added 'Mark Duplicate Records' option. When this option is turned on, all duplicate records are marked with different colors.