You work as the enterprise exchange administrator at Xxx .The Xxx network is running in a Microsoft Exchange Server 2010 environment.A SMTP server on the Internet has rejected some email sent from Xxx .What actions must you take to determine why this happened？（）

A.You must use the Windows Remote Management （WinRM） over SSL.

B.You must access the Send connectors and use the Verbose setting in the Protocol logging.

C.You must configure EdgeSync synchronization.

D.You must check the protocol log files.

E.You must implement a new managed content setting.