"You've Forefront TMG 2010, Exchange 2010 Edge role and Forefront Protection for Exchange (FPE) 2010 on same machine. You don't want to use Email policy configuration integration feature of TMG (TMG won't manage Exchange Edge and FPE settings), in other words you've not executed "Configure Email Policy" wizard in TMG Management console. In this situation E-Mail Policy settings appears like:
On Exchange Edge console you notice that default Receive Connector of Exchange Edge gets disabled:
Cause: TMG is responsible for this behavior because property IntegrationEnabled of SmtpProtectionConfiguration COM object is wrongly set to TRUE by default during TMG setup,"explained Microsoft.
To resolve "use integration mode so that TMG manages Exchange Edge and FPE settings automatically. However if you don't want to use this integration mode, current workaround to this problem is to set Email Policy Integration mode to Disabled and apply the change. This'll set the COM property IntegrationEnabled to False," advised Microsoft.