You need to be assigned permissions before you can perform this procedure. To see what permissions you need, see the "Recipient Provisioning Permissions" section in the Mailbox Permissions topic.

1. In the console tree, click Recipient Configuration.
   
2. In the result pane, select the recipient for which you want to configure message delivery restrictions.
   
3. In the action pane, under the recipient name, click Properties.
   
4. In <Recipient> Properties, click the Mail Flow Settings tab.
   
5. Select Message Delivery Restrictions from the list of mail flow settings, and then click Properties.
   
6. Message Delivery Restrictions   Select this setting and then click Properties to open the Message Delivery Restrictions dialog box. Use this dialog box to configure the following settings:
   All senders   Click this button to specify that the recipient can accept messages from all senders. This includes senders in both your Exchange organization and external senders. This button is selected by default. This option 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   Click this button to specify that the recipient can accept messages only from a specified set of senders in your Exchange organization. Click Add to open the Select Recipient dialog box. This dialog box displays a list of all recipients in the Active Directory forest. Select the recipients you want, and then click OK. You can also search for a specific recipient by typing its name in the Search box and then clicking Find Now.
   Require that all senders are authenticated   Select this check box to prevent anonymous users from sending messages to the recipient.
   No Senders   Click this button to specify that the recipient will not reject messages from any senders in the Exchange organization. This button is selected by default.
   Senders in the following list   Click this button to specify that the recipient will reject messages from a specified set of senders in your Exchange organization. Click Add to open the Select Recipient dialog box. This dialog box displays a list of all recipients in the Active Directory forest. Select the recipients you want, and then click OK. You can also search for a specific recipient by typing its name in the Search box and then clicking Find Now.
   
7. Click OK to return to the Mail Flow Settings tab.
   

You need to be assigned permissions before you can perform this procedure. To see what permissions you need, see the "Mail-enabled public folders" entry in the Mailbox Permissions topic.

1. In the console tree, click Toolbox.
   
2. In the result pane, click Public Folder Management Console, and then in the action pane, click Open Tool. The Public Folder Management Console appears in a separate Microsoft Management Console (MMC).
   
3. In the console tree, expand Default Public Folders, and then click the public folder that you want to configure. If the public folder you want to configure is a top-level public folder, click Default Public Folders.
   
4. In the result pane, click the public folder for which you want to configure message delivery restrictions.
   
5. In <Recipient> Properties, click the Mail Flow Settings tab.
   
6. Select Message Delivery Restrictions from the list of mail flow settings, and then click Properties.
   
7. Message Delivery Restrictions   Select this setting and then click Properties to open the Message Delivery Restrictions dialog box. Use this dialog box to configure the following settings:
   All senders   Click this button to specify that the recipient can accept messages from all senders. This includes senders in both your Exchange organization and external senders. This button is selected by default. This option 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   Click this button to specify that the recipient can accept messages only from a specified set of senders in your Exchange organization. Click Add to open the Select Recipient dialog box. This dialog box displays a list of all recipients in the Active Directory forest. Select the recipients you want, and then click OK. You can also search for a specific recipient by typing its name in the Search box and then clicking Find Now.
   Require that all senders are authenticated   Select this check box to prevent anonymous users from sending messages to the recipient.
   No Senders   Click this button to specify that the recipient will not reject messages from any senders in the Exchange organization. This button is selected by default.
   Senders in the following list   Click this button to specify that the recipient will reject messages from a specified set of senders in your Exchange organization. Click Add to open the Select Recipient dialog box. This dialog box displays a list of all recipients in the Active Directory forest. Select the recipients you want, and then click OK. You can also search for a specific recipient by typing its name in the Search box and then clicking Find Now.
   
8. Click OK to save your changes and return to the Mail Flow Settings tab.
   

You need to be assigned permissions before you can perform this procedure. To see what permissions you need, see the "Recipient Provisioning Permissions" section and the "Mail-enabled public folders" entry in the Mailbox Permissions topic.

The following procedure shows you how to use the Shell to configure message delivery restrictions for a mailbox. For other recipient types, use the corresponding Set- cmdlet with the same parameters.

This example configures the mailbox John Smith to accept messages only from the users Lori Penor, Jeff Phillips, and members of the distribution group Sales Department.

Set-Mailbox -Identity "John Smith" -AcceptMessagesOnlyFrom "Lori Penor","Jeff Phillips" -AcceptMessagesOnlyFromDLMembers "Sales Department"

Note:
If you're configuring a mailbox to accept messages only from individual senders, you must use the AcceptMessagesOnlyFrom parameter. If you're configuring a mailbox to accept messages only from senders that are members of a specific distribution group, you must use the AcceptMessagesOnlyFromDLMembers parameter.

This example configures the mailbox John Smith to require all senders to be authenticated.

Set-Mailbox -Identity "John Smith" -RequireSenderAuthenticationEnabled $true

This example configures the mailbox John Smith to reject messages from the users Joe Healy, Terry Adams, and members of the distribution group Sales Department Contractors.

Set-Mailbox -Identity "John Smith" -RejectMessagesFrom "Joe Healy","Terry Adams" -RejectMessagesFromDLMembers "Sales Department Contractors"

Note:
If you're configuring a mailbox to reject messages from individual senders, you must use the RejectMessagesFrom parameter. If you're configuring a mailbox to reject messages from senders that are members of a specific distribution group, you must use the RejectMessagesFromDLMembers parameter.

For detailed syntax and parameter information, see the following topics:

• Set-DistributionGroup
  
• Set-DynamicDistributionGroup
  
• Set-Mailbox
  
• Set-MailContact
  
• Set-MailPublicFolder
  
• Set-MailUser