There may be an occasion where you want to restore the original chronological view for the SMS Inbox rather than the new threaded view. One example is where a system programmatically moves or inserts SMS messages into the system because these are not visible in the threaded view (even though the count of unread messages increases). There is a simple registry fix to turn off threading and restore the "classic" view. From the registry editor of your choice browse the device registry for the key:
[HKEY_CURRENT_USER\Software\Microsoft\Inbox\Settings]
Under this add a new DWORD value called "SMSInboxThreadingDisabled" and set it to 1. Close the tmail.exe application or soft-reset the device and the regular message view will be used. Set this registry value back to 0 or delete it to restore the default threaded view.