Create mailbox message restrictions Exchange 2016

Message restriction can be useful to control who can send messages to users in your organization. For example, you can configure a mailbox to accept or reject messages from certain users or only to accept messages from your Exchange organization.

Message restriction can be configured using EMC or the Admin Center.

How to configure message restriction?

Open EAC (Exchange Admin center) navigate to Recipients > Mailboxes.

From the list of mailboxes, select the mailbox you want to configure message restrictions for and click Edit.

From the properties of the mailbox select Mailbox Features.

Under Message Delivery Restrictions, click View details to view or change the delivery restrictions

From the Message restrictions properties, the following options can be configured.

• Accept messages from   Use this section to specify who can send messages to this user.
  • All senders   This option specifies that the user can accept messages from all senders. This includes both senders in your Exchange organization and external senders. This is the default option. It includes external users only if you clear the Require that all senders are authenticated check box. If you select this check box, messages from external users will be rejected.
  • Only senders in the following list   This option specifies that the user can accept messages only from a specified set of senders in your Exchange organization. Click Add   to display a list of all recipients in your Exchange organization. Select the recipients you want, add them to the list, and then click OK. You can also search for a specific recipient by typing the recipient’s name in the search box and then clicking Search  .
  • Require that all senders are authenticated   This option prevents anonymous users from sending messages to the user. This includes external users that are outside of your Exchange organization.
• Reject messages from   Use this section to block people from sending messages to this user.
  • No senders   This option specifies that the mailbox won’t reject messages from any senders in the Exchange organization. This is the default option.
  • Senders in the following list   This option specifies that the mailbox will reject messages from a specified set of senders in your Exchange organization. Click Add   to display a list of all recipients in your Exchange organization. Select the recipients you want, add them to the list, and then click OK. You can also search for a specific recipient by typing the recipient’s name in the search box and then clicking Search 

For the purpose of the Post I will configure the following settings.

• Only Accept messages from senders in the list
• Reject messages from senders in the list

Click on Ok to save the changes.

How do we know this worked?

To test if our changes are I will send a message from John Hay to Jason May and according to the configuration the delivery of the message should fail.

I will select Jason May from the GAL and send him a test message.

As we can see the MailTips warns us that the user John Hay does not have the permission to send messages to Jason May.

If we ignore the MailTips and go ahead and still send the message we will receive the following message that the delivery failed.

Let’s go ahead and look at how we can configure the same message delivery restrictions using the Exchange Management Shell.

To start we need to launch the EMC and run the following.

The following parameters can be set for message delivery restrictions.

• AcceptMessagesOnlyFrom
• AcceptMessagesOnlyFromDLMembers
• RejectMessagesFrom
• RejectMessagesFromDLMembers
• RequireSenderAuthenticationEnabled

To verify the message delivery settings, use the following in EMC.

More details regarding message restrictions can be found here.

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