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.