You have an Exchange Server 2010 organization.
You deploy an Edge Transport server.
You need to implement a message hygiene solution that meets the following requirements:
Users must be able to receive e-mail from external recipients who have been added to their Safe Senders Lists
The Edge Transport server must block all e-mail sent to invalid addresses inside the organization

What should you do first?

A.
Enable sender filtering.

B.
Create Send connectors.

C.
Configure real-time block lists (RBLs).

D.
Configure EdgeSync synchronization.