This policy setting controls whether Outlook analyzes e-mail from users' Contacts when filtering junk e-mail.
If you enable this policy setting, the "Also trust E-mail from my Contacts" check box is selected in the Safe Senders tab of the Junk E-mail Options dialog and users cannot change it. E-mail addresses in users' Contacts list are treated as safe senders for purposes of filtering junk e-mail.
If you disable this policy setting, e-mail addresses in users' Contacts list are not treated as safe senders for purposes of filtering junk email, and users cannot change this configuration.
If you do not configure this policy setting, e-mail messages that are received from people who are listed in Contacts are considered safe by the Junk E-mail Filter, but users can change this configuration.