Since distribution groups contain multiple members, you may want to place restrictions on who can send messages to these recipients. Exchange allows you to tightly control these settings and provides several options when it comes to placing message delivery restrictions on groups. We can also place restrictions on other recipient types in the organization. This recipe will show you how to configure these options from the Exchange Management Shell.
To restrict who can send messages to a group, use the Set-DistributionGroup cmdlet:
Set-DistributionGroup -Identity Sales ` -AcceptMessagesOnlyFrom 'Bob Smith','John Jones'
After running this command, only the users Bob Smith and John Jones can send messages to the Sales distribution group.