You are here: Blog Outlook 2016 Autocomplete (nk2)

Outlook 2016 Autocomplete (nk2)

When you start an email and you start to type in an email address, OUTLOOK will show a drop-down list of email addresses you've written to before.

This is an AUTOCOMPLETE-list (This is not an address-book or contact-list). What's surprising to me is that, to users, this list is more important than the contact-list or address-book. Probably because it automatically show.

What's more suprising is that there is no connection between the contact-list, address-book or AUTOCOMPLETE-list.

History Autocomplete

The AUTOCOMPLETE file used to be called the NK2 file. There is a ton of information about the NK2 file.But it's 2017 and closing to 2018, the NK2 file is no longer relevant. The data on the internet is becoming long in the tooth. So much bad information.

Location Autocomplete

In any event, the AUTOCOMPLETE list in OUTLOOK 2016 is here:


The file name is something like:


!!!Step 1 For Autocomplete!!!

Before you do anything, copy this file as a backup!!! The file size is small and can be copied in less than 5 seconds. This file is known to be volitile and can go from a large size down to zero without warning. This is why you want a backup.

Transfer Autocomplete

If you have an old computer and OUTLOOK setup and your new comuter and OUTLOOK setup doesn't have the list, you can:

  • -close OUTLOOK.
  • -copy this file to the new computer.
  • -place in the following directory: C:\Users\foo.user\AppData\Local\Microsoft\outlook\RoamCache\
  • -rename the current DAT file to something like: Stream_Autocomplete_0_A603AC42FB764D4C9662D971D85637C2.dat.old
  • -change the wanted DAT file (with all the info in it) name to the current name, something like: Stream_Autocomplete_0_A603AC42FB764D4C9662D971D812345.dat

Export Autocomplete

You can export the names in the DAT file. Despite the name, the NK2EDIT is the best tool for this:

This will save the file as an NK2 file that can later be imported somewhere else.

Import Autocomplete

This is for a fresh OUTLOOK with no AUTOCOMPLETE.

  • -open the NK2 from the old system.

This will overwrite the existing AUTOCOMPLETE with the items from the old AUTOCOMPLETE.

Merge Autocomplete

This is to merge old AUTOCOMPLETE with the current AUTOCOMPLETE.

  • -open the NK2 from the old system.
  • (This will merge the current AUTOCOMPLETE with the info from the older AUTOCOMPLETE.)

This will overwrite the existing AUTOCOMPLETE with the items from the old AUTOCOMPLETE.

Rebuild Autocomplete

Let's say that the AUTOCOMPLETE file is gone. For whatever reason, it is emtpy (I'm bashfully looking away, avoiding eye contact). But you still have your PST/OST file. Can't you just rebuild the AUTOCOMPLETE with information that is in the SENT-ITEMS folder?

Yes, you can. Here's how:

  •  -open NK2EDIT (the list will be empty).

This will allow you to rebuild the AUTOCOMPLETE with items from your SENT-ITEMS folder. This is probably what you want; as everyone you've written an email to will automatically be placed in here. In addition, you can place a checkmark to items from your INBOX as well.

Fiddle around with the settings and when you are satisfied, click FILE > EXPORT-TO-MESSAGE-STORE.


  • -open NK2EDIT and edit away.

Final Thoughts

In short, this is an oldy but goody. Considering the importance of AUTOCOMPLETE items to users, you wonder why this isn't built directly into the OUTLOOK.


There is a POWERSHELL script that didn't exactly work for me but it looks promising if could be updated:


Contact Dak Networks

Please contact us at the following.