Autocomplete in Outlook 2010

Outlook 2010 and newer

Beginning with Outlook 2010, Outlook does not use the NK2 file; it stores the autocomplete cache in the mailbox or data file and caches the addresses in an autocomplete stream at

C:\Users\%username%\AppData\Local\Microsoft\Outlook\RoamCache

You can type or paste %localappdata%\Microsoft\Outlook\RoamCache in the address bar of Windows Explorer then press Enter to open the folder location where the cache is stored in a file named Stream_Autocomplete_0_[long GUID].dat.

Clear the autocomplete cache using the File, Options, Mail, Empty Auto-complete list button.