All employees at a company have Exchange Online mailboxes. You have a policy that allows users to send
email messages to a maximum of 500 specific recipients per message.
You need to grant User1 the ability to send email messages to 700 specific recipients per message.
What should you do?

A.
Add the recipients to a new distribution list. Instruct User1 to send email messages to the list.

B.
Run the following Windows PowerShell cmdlet:
Set-TransportConfig

C.
Run the following Windows PowerShell cmdlet and apply the policy to User1:
New-ThrottlingPolicy

D.
In the Exchange Admin Center, modify the mailbox properties for User1.

Explanation:
For distribution groups stored in an organization’s address book, the group is counted as one recipient.
Incorrect Answers:
B: The Set-TransportConfig cmdlet is usedto modify the transport configuration settings for the whole Exchange
organization, not for a single user.
C: A throttlingPolicy does not refer to the number of recipients of email messages.
https://technet.microsoft.com/en-us/library/exchange-online-limits.aspx#RecipientLimits