Key for Outlook 2007:
HKEY_CURRENT_USERSoftwareMicrosoftOffice12.0OutlookPreferences
Key for Outlook 2010:
HKEY_CURRENT_USERSoftwareMicrosoftOffice14.0OutlookPreferences
Key for Outlook 2013:
HKEY_CURRENT_USERSoftwareMicrosoftOffice15.0OutlookPreferences
Value name: ArchiveIgnoreLastModifiedTime
Value type: REG_DWORD
Value: 1
E-mail messages will now be archived based on their Received date, Calendar items based on their scheduled date and Task items based on their Completed date.