Outlook: Migration Automatic Completion

The automatic completion feature in Microsoft Outlook is one of those small conveniences that, while often unnoticed, are indispensable in everyday use of email. Whenever you start typing a name or address in the field “A”, “Cc” or “Ccn” of a new email, Outlook instantly proposes a list of suggested recipients, fished from our history. This system not only accelerates the composition of emails, but also drastically reduces the risk of typing errors, ensuring that messages always reach the right recipients.

However, when you change your computer, you update your Outlook version or reinstall the program, one of the most common inconveniences is just the loss of this valuable tips database. Manually rebuilding the list of all frequent contacts can be a long and frustrating process. Fortunately, Outlook automatic completion data is stored in specific files that can be managed and transferred. This complete guide will accompany you through the different procedures to recover, migrate and import these tips, ensuring you never lose the efficiency offered by this convenient function, regardless of the version of Outlook in use.

Understand Outlook Automatic Completion Files

Before immersing ourselves in transfer procedures, it is essential to understand how Outlook stores automatic completion data. Over the years, Microsoft has modified the format and location of these files, leading to two main types which is crucial to distinguish:

• The NK2 file: The Legacy Format
  Outlook versions until 2007 (included) used an extension file .NK2 to save all automatic completion tips. This file is relatively simple to manage and, for older versions, its transfer consisted mainly of copying it to the correct folder. It was a robust format for its time, but with the evolution of Office, it was replaced by a more modern solution.
• The DAT file (Stream Autocomplete 0 [xxx].dat): The Modern Format
  From Outlook 2010, the file .NK2 was abandoned in favor of a new format, a file .dat with a name of the type Stream_Autocomplete_0_[xx].dat (where) [xx] indicates an alphanumeric sequence that varies). This new file is part of a more integrated and robust system, but its introduction created a challenge: how to import data from old NK2 files into new Outlook versions? The procedures we will follow will solve this problem, allowing you to bridge the gap between the two formats.

Knowledge of these two types of files is the key to smooth migration, since the steps vary significantly depending on whether you are working with a previous version of 2010 or later.

Locate Automatic Completion Files on Your Computer

The first step in any suggestions management operation is to locate the automatic completion file on your computer. Positions vary slightly depending on the version of Windows and Outlook. Here's how to find them:

For NK2 Files (Outlook 2007 and Preferred on Modern Windows)

If you use an Outlook version equal to or prior to 2007 on a modern Windows operating system (View, 7, 8, 10 or later), the file .NK2 is typically located in the following path:

C:UserstuonomeAppDataRoamingMicrosoftOutlook

Where “you name” must be replaced by the username of your Windows profile.

To quickly access this folder, you can use the Windows “Run” panel:

1. Press the key combination Win + R on the keyboard to open the window “Execute”.
2. In the text field, type (or paste) the command: %appdata%MicrosoftOutlook
3. Press Send.

The desired folder will open directly. Here you should find the file called Outlook.NK2 (or a similar name that matches the name of your Outlook profile if different from “Outlook”). Copy this file to a USB stick or another secure location for transfer.

For NK2 files on Windows XP

For Windows XP users, the file path .NK2 is slightly different:

C:Documents and SettingstuonomeDati applicazioniMicrosoftOutlook

Also in this case, “tuonome” refers to the username of the system. The procedure for accessing it is similar, using the “Run” panel and the complete path.

For DAT Files (Outlook 2010 and Successive)

For the latest versions of Outlook (from 2010 onwards), the file Stream_Autocomplete_0_[xx].dat is located in a different folder, inside the directory “Local” instead of “Roaming”:

C:UserstuonomeAppDataLocalMicrosoftOutlookRoamCache

Also for this folder, you can use the “Run” panel by typing: %localappdata%MicrosoftOutlookRoamCache and pressing Send.

It is always advisable to backup this file before proceeding with any modification, especially if you want to overwrite it.

Transfer the Automatic Completion Data: Basic procedure

The simplest transfer takes place between Outlook versions that use the same file format (NK2 with NK2, or DAT with DAT). This is the ideal situation when moving Outlook from one PC to another while maintaining the same version of the software.

Transfer of NK2 Files (Outlook 2007 and Precedents)

If you need to transfer suggestions between two Outlook 2007 installs (or previous versions), the procedure is extremely direct:

1. Make sure Outlook is completely closed on the target computer.
2. Copy the file Outlook.NK2 (or the NK2 file with your profile name) from your source PC.
3. Paste it into the corresponding folder on the target PC: C:UserstuonomeAppDataRoamingMicrosoftOutlook (or the path for Windows XP, if applicable).
4. If you are asked to overwrite an existing file, agree.
5. Start Outlook. Your automatic completion tips should be immediately available.

DAT File Transfer (Outlook 2010 and Successive)

Similarly, if you are migrating the suggestions between two Outlook 2010 installs, 2013, 2016 or later, where both use the file .DAT:

1. Completely close Outlook on the target computer.
2. Copy the file Stream_Autocomplete_0_[xx].dat from the PC of origin.
3. Paste it into the folder on the target PC: C:UserstuonomeAppDataLocalMicrosoftOutlookRoamCache.
4. It is essential that the copied file has exactly the same file name .DAT already present on the target PC to ensure that Outlook recognizes it correctly. If the names are different, rename the newly copied file to make it match the existing one (after making a backup).
5. Start Outlook. Suggestions should be restored.

Import NK2 Files in Outlook 2010 and Successful Versions (Fusion Method)

This is the most requested and slightly more complex procedure, since it involves converting and integrating an older NK2 file into an Outlook installation that uses the DAT format. Outlook 2010 and later versions include an internal feature to directly import NK2 data.

Step 1: Preparation of the NK2 File

1. Check Outlook Profile Name: In order for the import to work correctly, the name of your NK2 file must match the name of your active Outlook profile.
   • Open the “Control Panel” of Windows (trying it in the Start menu).
   • Click on “User Account” (or “User Account and Family Safety”, then “User Account”).
   • Select “Electronic button (Microsoft Outlook 20xx)” or similar (the name may vary depending on the version).
   • In the mail setting window, click on “Show profiles...”.
   • Take note of the name of your Outlook profile (often it is “Outlook” by default, but it could be different).
2. Rename the NK2 File: If your NK2 file name (for example, Outlook.NK2) does not match the profile name you have just verified (e.g., “MioProfile”), name it accordingly (e.g, MioProfilo.NK2).
3. Copy the NK2 file in the Correct Folder: Copy the renamed NK2 file to Outlook data folder, although this version does not use it directly for autocomplete: C:UserstuonomeAppDataRoamingMicrosoftOutlook. You can access it quickly with Win + R and typing %appdata%MicrosoftOutlook.

Step 2: Execution of the Import Command

Once the NK2 file is in the correct and renamed location, you can start the import process:

1. Make sure Outlook is completely closed.
2. Open the “Execute” panel again (Win + R).
3. Type (or paste) the command: outlook.exe /importnk2
4. Press Send.

Outlook will start and, if everything has been executed correctly, it will automatically import all the suggestions present in the NK2 file, adding them (phoning them) to the existing auto completion list in your modern Outlook installation. This data will then be saved in your file Stream_Autocomplete_0_[xx].dat.

Clear Existing Tips Before Importing (Optional)

If you want a clean list, without the old tips before importing the NK2 file, you can empty the Outlook auto completion list:

1. Start Outlook normally.
2. Click on File (top left).
3. Select Options.
4. In the Outlook Options window, choose Post from the left sidebar.
5. Scroll down to the “Send Messages” section and click on the button Empty automatic completion list.
6. Close Outlook and then proceed with the import procedure NK2 described above.

Alternative method: Using NK2Edit for Conversion and Importation

If the direct import procedure does not work, or if you prefer to have a more granular data control, there is an excellent third-party utility called NK2Edit. This free and portable tool allows you to view, edit and convert NK2 and DAT files, offering a versatile solution for managing automatic completion tips.

Step 1: Download and Prepare NK2Edit

1. Download NK2Edit: Search “NK2Edit download” online and download the software from the official website. Make sure you download the version “in zip File”.
2. Extract the Content: Once you download the ZIP file, extract the content to a folder of your choice on your computer. Being a portable program, it does not require installation.
3. Existing DAT File Backup: Before proceeding, it is essential to create a backup copy of your current file Stream_Autocomplete_0_[xx].dat. Find this file in: C:UserstuonomeAppDataLocalMicrosoftOutlookRoamCache. In case of problems, you can restore your original suggestions.

Step 2: Convert and Replace the File

1. Close Outlook: Make sure Microsoft Outlook is completely closed before starting NK2Edit and making any changes.
2. Start NK2Edit: Double-click the NK2Edit executable within the folder where you extracted it.
3. Open the NK2 file: In the program, go up File > Open and select the file .NK2 that you want to import. You can view all contacts and suggestions in it.
4. Save as DAT File: Now, go to the menu File > Save as. From the drop-down menu “Save as”, select the option Outlook 2010 AutoComplete .dat file (Stream Autocomplete*. dat).
5. Overwrite the Existing DAT File: Save the new converted DAT file directly to the folder C:UserstuonomeAppDataLocalMicrosoftOutlookRoamCache, overwriting the file Stream_Autocomplete_0_[xx].dat existing (what you did backup).

Once the operation is completed, start Outlook. The program will upload the new DAT file, and all automatic completion suggestions from your old NK2 file will be available. Unlike the melting method, this procedure completely overwrites existing suggestions with those of the converted NK2 file.

Final considerations

The management and migration of Outlook automatic completion tips, although it may seem a technical task, is actually a well documented and feasible process. Whether you are making a simple transfer between identical versions or a more complex import between different formats, solutions exist and are at hand.

Always remember the importance of backing up your original files before taking any editing or overwriting procedure. This precaution will guarantee you the opportunity to go back in case of unexpected. With the directions provided, your experience with Outlook will remain smooth and productive, without frustrating losing one of its most useful features.