Outlook's auto complete email addresses nicknames .nk2

Use the steps in the following section to find the Outlook nickname cache (auto complete suggestions) for Microsoft Windows XP.
1. Quit Outlook.
2. Click Start, and then click Search.
3. In the Search Companion left-side panel, click All files or folders.
4. In the All or part of the file name: box, type *.NK2.
5. In the Look In box, click to select your local hard disk.
6. Click More advanced options, click to select Search hidden files and folders check box.
7. Click Search.

Note: if your computer returns no results you can navigate to the following folders:
C:\Documents and Settings\YOUR USERNAME\Application Data\Microsoft\Outlook
or in Windows 7: C:\Users\YOUR USERNAME\AppData\Roaming\Microsoft\Outlook
When we searched even with hidden files turned on it brought back no results so we had to navigate to the location.

8. Right-click the .NK2 file with the name of the profile that you want to reuse/recover, and then click Rename.
9. Rename the new file to profilename.bak, and then press ENTER.

Then rename your old or existing .NK2 file to the current name of your profile and your existing email addresses should show up once you reopen Outlook.

10. Quit Windows Explorer.
11. Restart Outlook.

Note: If you are using Outlook 2010 and need to import your Nickname file .nk2 you will need to follow this article.


Nickname files are not longer used in Outlook 2010.

Outlook 2013 –
To import .nk2 files into Outlook 2013, follow these steps: 

  1. Make sure that the .nk2 file is in the following folder:

    Note The .nk2 file must have the same name as your current Outlook 2013 profile. By default, the profile name is ‘Outlook.’ To check the profile name, follow these steps:

    1. Click Start, and then click Control Panel.
    2. Double-click Mail.
    3. In the Mail Setup dialog box, click Show Profiles.
  2. Click Start, and then click Run.
  3. In the Open box, type outlook.exe /importnk2, and then click OK. This should import the .nk2 file into the Outlook 2013 profile.Note After you import the .nk2 file, the contents of the file are merged into the existing nickname cache that is currently stored in your mailbox.

Note The .nk2 file is renamed with a .old file name extension on the first start of Outlook 2013. Therefore, if you try to re-import the .nk2 file, remove the .old file name extension.


Even though Outlook 2010 does not have a NK2 file, it does still store the info in a file, but with a different name. The name of the file is;:


And it’s located in here:


If you are on Windows XP with Outlook 2010, then it’s here:

C:\Documents and Settings\Username\Local Settings\Application Data\Microsoft\Outlook\RoamCache

Close Outlook, if it’s open.  Once you locate this folder you can normally identify your file because it should be larger than 19kb.  If that’s the case, copy the latest two files to another folder so you have a backup.  Then take the smaller file name and rename it to .old and then copy the name of that file (minus the .old) and rename the larger file to exactly the same name.  Open outlook give it 15 to 30 seconds to register the file change then open a new email and check to see if it starts populating the emails addresses.  If for some reason it clears your file you will need to attempt this again from the backup of the files you took.  In some cases, if it didn’t work the first time it almost always worked the second time.

If Office shows that it’s not installed in Add/Remove programs (but the apps are actually working) then your Stream file may be located in this path: C:\Users\%username%\AppData\Local\Packages\Microsoft.Office.Desktop_8wekyb3d8bbwe\LocalCache\

See below for the screen shot.

Importing the nk2 file in Outlook 2010, Outlook 2013 and Outlook 2016 cont..
When you upgrade to Outlook 2010, Outlook 2013 or Outlook 2016, the nk2 file is automatically imported upon starting Outlook for the first time.

Copy the nk2 file to the following folder;
Rename the nk2 file to the name of your mail profile.
To find out this name use the Mail icon in Control Panel and click on the Show Profiles button.

By default, your profile is called “Outlook”. So in that case you would call your file “outlook.nk2”.

Start Outlook with the /importnk2 parameter;
Start-> type; outlook.exe /importnk2
Outlook will now process the nk2 file and import it Outlook. (Outlook 2013 and later no longer use this file).  Outlook will automatically change the name to .old on the nk2 file. So for example it will now be called; outlook.nk2.old

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