HOTSPOT
You deploy a new Exchange Server 2016 organization. The organization contains Two Mailbox servers.
You need to reject email messages if a redundant copy of the messages cannot be generated.
What command should you run? To answer, select the appropriate options in the answer area.
Hot Area:
Answer: 
Explanation:
https://technet.microsoft.com/en-us/library/dd351027(v=exchg.150).aspx
https://technet.microsoft.com/en-us/library/bb124151(v=exchg.160).aspx
Good links, Agree with answers:
The RejectMessageOnShadowFailure parameter specifies whether to accept or reject messages when shadow copies of the messages can’t be created. Valid values are:
$true Messages are rejected with the SMTP code 450 4.5.1. Use this value only if you have multiple Mailbox servers in a database availability group (DAG) or in an Active Directory site where shadow copies of the messages can be created.
$false Messages are accepted without making shadow copies. This is the default value.
The number of attempts to make a shadow copy of the message and where to make the shadow copy are controlled by the MaxRetriesForLocalSiteShadow, MaxRetriesForRemoteSiteShadow, and ShadowMessagePreferenceSetting parameter settings.