You deploy a new Exchange Server 2010 organization. You send a test message to an external recipient and immediately receive the following non-delivery report (NDR):

“Delivery has failed to these recipients or groups: User1@contoso.com (user1@contoso.com). The recipient’s email system isn’t accepting messages now. Please try resending this message later or contact the recipient directly.”

You verify that you can successfully send an email message to User1@contoso.com from an external email system.

You need to ensure that you can send emails to external recipients from within the Exchange organization.

What should you create?

A.
A Send connector.

B.
An accepted domain.

C.
An MX record.

D.
An SMTP site link.

Explanation:
Reference:

http://technet.microsoft.com/en-us/library/bb232045.aspx