A user wanted to know how to move their auto-complete list in Outlook 2010:
"We're switching from Google Apps to Office 365. Can we migrate auto-complete addresses to the new accounts? We don't have an NK2 to import."
The auto-complete list is stored in .dat files in the RoamCache folder under the Local AppData folders. You can access this folder by typing or pasting the following command into the address bar of Windows Explorer and pressing enter.
You can use a utility to extract the addresses from the auto-complete stream and insert them into the new auto-complete stream. Or you could rename the .dat file with the name of the new .dat file, however, because the auto-complete tends to corrupt easily, make sure you export the addresses to a CSV file first, otherwise you might lose the addresses.
See Auto-Complete or Nickname Cache (*.NK2) Utilities for utilities that can recover addresses from the auto-complete cache or NK2 file.