How to Rebuild Outlook Email Autocomplete

Oct 2009

How to Rebuild Outlook Email Autocomplete

comment icon3 comment(s) |

Recently my Outlook email autocomplete quit working.   This is the nice feature that will autocomplete email addresses after you've entered them in one time previously.  This saves a ton of time so that you don't have to:

  • Look up email addresses for people that you email infrequently
  • Type in the entire email address for someone

It also keeps you from accidentally mis-spelling an email address.

After a little research I found that my .NK2 file was most likely corrupted.  This is the file that Outlook stores the autocomplete information in.  I renamed that file (located in \documents and settings\<profile>\Application Data\Microsoft\Outlook), but all it did was reset the autocomplete.

Luckily I found a free app that will rebuild your .NK2 file based on all of your sent email, a very handy tool.  The tool can be found here, .  It will scan your sent emails and compile all of the email addresses you have sent to and add them to the list.  

The only downside was that it did not import the addresses in the address book, but I was easily able to add everyone in our company by following these steps:

  • Open a new email
  • Click "TO"
  • Select everyone
  • Click "OK"

No need to send the email, just close it because the names have already been added to the autocomplete index at that point.



October 19, 2009


Outlook Autocomplete

Odd. I had a similar (but different) problem which started last Friday. I think my issue was caused by an Outlook add-in product I use called Xobni.

I had to run the ScanOST.exe utility and then change the config of Xobni to get my autocomplete to work again and to prevent it from a memory leak which totally locked-up my computer.

Everything appears to be working properly now that I have turned-off the Xobni auto-complete add-in.


November 10, 2009



This is simply killer. After clearing HDD and installing Win7, my autocomplete was gone. This fixed in minutes.

Great share.

November 29, 2012


Updated Article

As the link above no longer goes a valid website, you can visit for an alternate list of links explaining how to rebuild the nk2 file.