Clear Cached Email Addresses From Outlook 2007, Outlook.NK2 Editing

Over the past couple of years I have been using the same Outlook files which have over time built up a huge cache of invalid e-mail addresses, e-mail address that are no longer used, and various other e-mail addresses I want to remove from the e-mail address cache. The cache that I am talking about is when you compose a new message and then start typing an address into the To, CC, or BCC field it begins to auto complete. On numerous occasions I have mistyped my own address and sent emails which now brings up numerous emails similar to my own and I have to make sure I select the proper one each time. Needless to say I needed to figure out what Outlook 2007 cache file stores these messages and how to edit that file to remove and modify addresses.

The file that stores cached email addresses in Outlook is called Outlook.NK2 and is located in the %APPDATA%\Microsoft\Outlook folder. To get to the location of this file click the Start button, select Run from the pop up menu, type “%APPDATA%\Microsoft\Outlook” into the Run field, and click Enter. This will open up Outlook 2007 Application Data folder where the Outlook.NK2 file is located. This is a Outlook Data File which cannot be edited with a normal editor so luckily someone has created an application to edit, backup, and restore this file. The name of this application is NK2View and below are some basic tips for using the application including where to download it.

Download NK2View Here: NK2View Download

  • Download, Unzip, and Click nk2view.exe to run the application
  • Make sure to close Outlook before running the above application
  • Make a backup of Outlook.NK2 before making any modifications

Using NK2View is simple and includes menu items to backup, restore, and modify the NK2 file. Below is an image of what the application looks like.

NK2View: Edit Outlook Email Address Cache

Just remember to backup the Outlook.NK2 file, which can be done from within NK2View,  before making any modifications.

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