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Outlook Copy Export Autocomplete List File

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Outlook Copy Export Autocomplete List File

To copy or export your Outlook autocomplete list (the names that pop up when you start typing in the To field), you need to locate and copy a file called NK2 (Outlook 2010 and earlier) or a Stream_Autocomplete entry in a hidden mailbox folder (Outlook 2013 and later). This article explains exactly where those files live, how to back them up or move them to another computer, and what to do when the list won’t copy over.

What the Autocomplete List Is and Why It Matters

Outlook’s autocomplete list, sometimes called the nickname cache, stores the email addresses and display names you’ve typed into the To, Cc, and Bcc fields. It’s separate from your Contacts folder, and it’s what makes Outlook suggest recipients as you type. If you lose it, you lose years of typing shortcuts, and rebuilding it manually is tedious.

The list is not stored as a simple .csv or .txt file you can open in Notepad. It’s a binary file (or a hidden mailbox item) that Outlook reads directly. That’s why copying it isn’t as straightforward as exporting a contact list—you’re moving a proprietary data file, not a readable document.

Where Outlook Stores the Autocomplete File by Version

The location and format changed with Outlook 2013, so the first thing to know is which version you have.

  • Outlook 2010 and earlier: The file is named ProfileName.nk2 (for example, Outlook.nk2). It lives in the Application Data\Microsoft\Outlook folder under your user profile. On Windows 7 and earlier, that path is typically C:\Users\YourName\AppData\Roaming\Microsoft\Outlook\Outlook.nk2.
  • Outlook 2013, 2016, 2019, and Microsoft 365: The list is no longer a standalone .nk2 file. Instead, it’s stored as a hidden message in your mailbox, inside a folder named Autocomplete under Conversation Action Settings. The actual data is in a stream named Stream_Autocomplete. You can’t see it in the normal folder pane; you have to use a tool like NK2Edit or a manual Registry/export method to extract it.

For Outlook 2013 and later, the autocomplete data is synced with your mailbox if you use Exchange or Microsoft 365, which means it follows you to other devices. But for POP/IMAP accounts, it’s stored locally in the mailbox data file (.ost or .pst), and copying it requires a different approach.

How to Copy the Autocomplete List (Step-by-Step)

Here’s how to actually get the list out, depending on your Outlook version.

For Outlook 2010 and Earlier (NK2 File)

  1. Close Outlook completely.
  2. Open File Explorer and paste this into the address bar: %appdata%\Microsoft\Outlook.
  3. Look for a file named Outlook.nk2 (or YourProfileName.nk2).
  4. Copy that file to a USB drive or network location.
  5. On the new computer, close Outlook, then paste the file into the same folder. If Outlook is already running, the file will be overwritten when you close it, so close it first.

For Outlook 2013 and Later (Stream_Autocomplete)

There’s no simple file to copy. The easiest reliable method is to use a third-party tool like NK2Edit (which works with the newer format too) or to use the built-in Export feature in Outlook’s File > Open & Export > Import/Export—but note that the standard export does not include the autocomplete list. The official way is:

  1. In Outlook, go to File > Options > Mail.
  2. Under Send messages, check Use Auto-Complete List and click Empty Auto-Complete List only if you want to clear it (don’t do that to copy).
  3. To actually export, use a tool like NK2Edit (free for personal use) that reads the hidden stream and can save it to a .nk2 file or export to CSV.
  4. On the new computer, open NK2Edit, import the .nk2 file, and then close Outlook and reopen it—the list should appear.

If you’re comfortable with the Registry, you can also export the key HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Profiles\Outlook\9375CFF0413111d3B88A00104B2A6676 (the number varies by profile), but that’s risky and rarely needed.

Common Problems and Fixes When Copying

  • The .nk2 file won’t copy because Outlook is running. Outlook locks the file. Close it completely, including the system tray icon.
  • Autocomplete list is empty after copying. The list is stored per profile. If you copied the file to a folder but Outlook created a new profile, it won’t read the old file. Make sure you’re using the same profile name.
  • For Outlook 2013+, the list doesn’t appear on the new computer. If you’re using Exchange, the list syncs automatically—just wait a few minutes. If you’re using POP/IMAP, the list is in the .pst file, so you need to copy the entire .pst, not just the autocomplete stream.
  • The list is huge and you only want a few addresses. You can’t selectively export from the built-in UI. Use NK2Edit to view and delete individual entries, then export the whole thing.

Alternative: Export Contacts vs. Autocomplete

Many people confuse the autocomplete list with their Contacts folder. Exporting contacts (File > Open & Export > Import/Export > Export to a file > CSV) gives you a readable list of all your saved contacts, but it does not include the addresses you’ve typed without saving them as contacts. If you want to move your entire email address history, you need both: export contacts as CSV, and copy the autocomplete file as described above.

If you’re moving to a new computer and you only care about the addresses you actually use, you could also just export your Sent Items folder as CSV and extract the To addresses from there—it’s a rough workaround but often covers most of the same people.

Safety and Accuracy Notes

Copying the autocomplete file is safe if you follow these rules:

  • Always close Outlook before copying or replacing the file. Otherwise, Outlook may overwrite your changes when it exits.
  • Back up the original file first. If something goes wrong, you can restore it.
  • Don’t edit the .nk2 file with a text editor. It’s binary; you’ll corrupt it.
  • The autocomplete list is tied to your Windows user profile. If you copy it to a different Windows user account on the same computer, it won’t work unless you place it in that user’s AppData folder.

Also note: Microsoft deliberately changed the format in 2013 to make it harder to copy, partly because the list can contain sensitive addresses. If you’re copying it to a non-work device, be aware that you’re moving personal email data.

Frequently Asked Questions

Can I export the autocomplete list to Excel?

Not directly from Outlook. You can use a third-party tool like NK2Edit to export the list to CSV, which you can open in Excel. The built-in export options don’t include the autocomplete list.

Does the autocomplete list sync between computers automatically?

Only if you use an Exchange, Microsoft 365, or Outlook.com account. For POP/IMAP accounts, the list is stored locally and does not sync. If you use a hybrid setup (e.g., IMAP with a local .pst), you’ll need to manually copy the file.

Why is my .nk2 file empty or missing?

If you’re using Outlook 2013 or later, the .nk2 file doesn’t exist anymore. If you’re on an older version and the file is empty, it might be because you’ve never typed enough addresses, or because Outlook is set to not use autocomplete (File > Options > Mail > Use Auto-Complete List).

Can I merge two autocomplete lists from different computers?

Yes, but not with built-in tools. NK2Edit can merge two .nk2 files into one. For the newer format, you’d need to export both to .nk2, merge, and then import back.

Is there a way to clear the autocomplete list without deleting the file?

Yes. In Outlook, go to File > Options > Mail, scroll to Send messages, and click Empty Auto-Complete List. This removes all entries but keeps the file intact.

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