Outlook 2002 and 2003 attempt to auto-complete name and email addresses typed into the To:, Cc:, Bcc: and From: fields of messages. Anyone using Outlook for sometime will know this feature saves a great deal of time and almost eliminates looking up email addresses once they’ve been cached. The big problem, and the reason for this article, is that the cache isn’t validated or checked against changes in the address book.

Relying heavily on the auto-complete feature can be a problem when a contact’s email address changes or if an address with a typo is cached. Outlook doesn’t provide a way to update or validate the cached addresses. …except when addresses get flushed. With current Outlook versions an .NK2 file only holds the 1,000 most-recent email addresses.

There are two ways, that I know of, to “fix” the cache. The first method edits the file from within Outlook and the second method clears the cache completely:

Editting Specifc Names in Outlook .NK2 Cache Files:
To edit the cache, just start a new message in Outlook. In the address field start typing the name or address necessary to make Outlook show the selection list that contains the incorrect email address. Press the down arrow to select the incorrect address and then press the delete key. The address that was selected will be deleted from the .NK2 file - the correct address will be added as soon as it is used in an email.

Resetting/Clearing the Outlook Auto-Complete Cache:
The cache can easily be reset by searching for and deleting the “Outlook.NK2″, “MS Exchange Settings.NK2″ or other *.NK2 file associated with a particular Outlook user account. On Windows XP desktops these files are typically in %userprofile%\Application Data\Microsoft\Outlook. Generally the “Outlook.NK2″ file will be the correct one to delete to clear auto-complete information. If there are multiple Outlook profiles created in one Windows User Profile, then additional .NK2 files are typically named after the profile.

5 Responses to “Removing Email Addresses & Names From Outlook 2002 & 2003 Auto-Completion Address Field (.NK2 File Editing)”

1. Marc Scheuner, on January 2nd, 2006 at 1:09 am, said:
   

   There’s two utilities I’m aware of to deal with .NK2 files:

   1) Interactive NK2 editor by Ingressor:
   http://www.ingressor.com/
   $35 shareware

   2) Free NK2-to-CSV export utility:
   http://www.epute.com/nk2csv/

   Hope this helps!
   Marc

2. daimo, on March 20th, 2006 at 9:46 pm, said:
   

   Mr Tweak,

   Love your work… very handy indeed!
   Just solved a problem that has been quitely getting on my nerves and the nerves of a few of my workmates for sometime!

   Keep up the good work!

   daimo

3. Mike Bijon, on March 23rd, 2006 at 3:35 pm, said:
   

   Thanks daimo, that’s the whole idea. Not enough profressional IT people share their knowledge with others (actually most of the guys who have worked for me don’t even like documenting what they’ve done when it’s their job to do just that).

   Hope you can find something else useful another time too.

4. rianna, on April 10th, 2006 at 12:12 pm, said:
   

   I am having trouble deleteing my email address i need to delete it but i can’t what should i do ?

5. Mike Bijon, on April 14th, 2006 at 4:41 pm, said:
   

   Rianna, are you talking about Outlook or Hotmail? You email address is “@hotmail.com”, and I’m not very familiar with Hotmail.

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