Methods to Migrate Outlook AutoComplete Cache

Problem:

When migrating mailboxes between Exchange servers, Exchange to Exchange Online (Office 365) or between Office 365 tenants—the Outlook AutoComplete list doesn't transfer automatically. This list, which suggests email addresses as you type in the To, Cc, or Bcc fields, is stored as a hidden message in the mailbox. Since most migration tools don't include this hidden data, users may find that their frequently used email suggestions are missing after the migration.

Solution:

There are two methods for transferring your AutoComplete cache to a new environment, and the appropriate method depends on the version of Outlook you're using on your old system.

Method 1: Outlook 2007 and earlier

Method 2: Outlook 2010 and later

Method 1: Outlook 2007 and earlier

In Outlook 2007 and earlier, AutoComplete suggestions are stored in a .nk2 file, which tracks frequently used email addresses. This file is saved in the following folder on your computer:

%AppData%\Microsoft\Outlook

To migrate your AutoComplete data to a newer version of Outlook, you'll need to manually transfer this .nk2 file. Here's how:

1. Locate the .nk2 file on your old computer and copy it.
2. On your new computer, navigate to the same folder path and paste the .nk2 file there.
3. To import the AutoComplete list, press Windows + R to open the Run dialog.

   In the dialog box, type the following command:

   outlook /importnk2

4. Press Enter.

After completing these steps, Outlook will automatically load your previously saved AutoComplete suggestions. If you need further help, you can refer to this Microsoft support page for more detailed instructions.

Method 2: Outlook 2010 and later

In Outlook 2010 and newer versions, AutoComplete data is no longer stored in a separate file like older versions. Instead, it’s saved as a hidden message within your mailbox, specifically in the Inbox folder. This hidden item holds the entire list of email addresses Outlook has remembered over time.

Because this data is hidden, you can’t access or transfer it directly through Outlook. To move it to a new system or a different Outlook profile, you’ll need to use a free tool called MFCMAPI, which allows you to view and manage these hidden mailbox items.

How to transfer AutoComplete using MFCMAPI?

1. On the old computer:
   • Open MFCMAPI and sign in to your Outlook profile.
   • Navigate to: Root Container > Top of Information ✔Store > Inbox (or IPM_SUBTREE)
   • Look for a message named IPM.Configuration.Autocomplete
   • Right-click it and choose Export Message.
   • Save the file as a .msg file.
2. On the new computer:
   • Launch MFCMAPI and log in to the Outlook profile you want to restore the data to.
   • Go to the same Inbox location.
   • Use the Import Message option and select the .msg file you exported earlier.

After completing these steps, your AutoComplete suggestions should be available in the new Outlook environment.

For full step-by-step instructions, refer to the official Microsoft guide (look for the section on copying the AutoComplete list in Outlook 2010 and later)