You have an Exchange Server 2010 organization that contains five Hub Transport servers， five Mailboxservers and one Edge Transport server.  You need to provide a solution to ensure that users can prevent legitimate inbound e-mail messages frombeing classified as spam.  What should you do？（）

• A、Enable sender filtering.
• B、Enable Sender ID filtering.
• C、Configure a custom MailTip.
• D、Configure safelist aggregation.