Outlook Auto Complete and the NK2 File

My wife’s absolutely favorite feature of Outlook is the fact that she can use the auto complete feature to address her emails.  I will never forget when I had to setup her computer fresh and reinstall all the software. Back then I did not know about the NK2 file. All I knew is she asked where her email address shortcuts went and I of course did not have a clue.

So after some research I learned about the NK2 file. By moving and backing up this file I could always give my wife her favorite feature if I ever had to reinstall Outlook or get her updated on the laptop for travel, etc. with the most recent version of her auto complete list.

This file resides on your hard drive if you have Outlook 2003 or 2007 versions. If you have the latest version, Outlook 2010, the NK2 file is no more.

However, the feature is not lost – let me explain.

In Outlook 2003 and 2007 the NK2 file used for auto complete is located at Drive:\Documents and Settings\Your User Name\Application Data\Microsoft\Outlook\.  This is a hidden directory so you will need to choose to view those hidden folders in order to drill down to that directory and find the file.

The change that has occurred in Outlook 2010 is not the removal of the auto complete feature – just where that list is stored and how it is presented in Outlook itself.

The actual files related to the auto complete feature have been moved to Drive:\Users\Your User Name\AppData\Local\Microsoft\Outlook\RoamCache\ and they begin with Stream_Autocomplete_ and have a file suffix of .dat.

If you open up Outlook 2010 and look at the Contacts tab you will see some new contact listings for each of your email accounts that have email addresses in the auto complete file called Suggested Contacts.

These lists of contacts can not be removed within Outlook as a whole and if you click on them you will see the collection of email addresses that are in your auto complete list for that account. You can remove individual address in the Contact Pane and that will remove them from the auto complete list. 

I did try adding someone to the Suggested Contacts list to see if they show up in the auto complete list but it did not work. E-mail addresses are still added to the auto complete/Suggested Contacts list once you have sent an e-mail to that individual.

However, I was able to remove an entry from a Suggested Contact listing and they were removed from the auto complete list so this does provide a little bit of built in editing capability of the auto complete list – at least to remove entries.

Have you learned any tricks about Outlook or any other Office programs? Please share them with everyone in the comments. Thanks!

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Richard Hay  (3349 Posts)

Richard is the Owner of WindowsObserver.com and has been involved in tech for over 25 years. His first website – AnotherWin95.com – came online in 1995. Back then he used GeoCities Web Hosting for it and what you see here today is the result of the work he has continued on the site since 1995. In January 2010 his community contributions were recognized by Microsoft when he was awarded the Most Valuable Professional (MVP) Award for Windows Desktop Experience. In January 2011 he was renewed as a Microsoft MVP but in a new category called Windows Expert - Consumer and in January 2012 he received the award for the third time.