Added Files

Powershell/PowerShell-Office365Admin/ExchangeWithMFA/BlockEmailForwardingToSpecificDomains.ps1

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+# Create a rule to block email forwarding to specific domains.
+#
+# Uses the new PowerShell "module" that support MFA.
+#
+
+# What domains are we blocking?
+$domainListFile = 'C:\Temp\DomainList.txt'
+
+# What do we want to call the rule?
+$ruleName = 'Block Auto Forwarding to Specific Domains 4'
+
+# What reason do we want end users to see for the rejection?
+$rejectionReason = 'Auto forwarding messages to this email provider is not permitted.'
+
+# Find and load the new ExO "module"
+$exoModulePath = (Get-ChildItem -Path $env:userprofile -Filter CreateExoPSSession.ps1 -Recurse -Force -ErrorAction SilentlyContinue).DirectoryName[-1]
+. "$exoModulePath\CreateExoPSSession.ps1"
+
+# Establish a session to Exchange Online
+Connect-EXOPSSession
+
+# Get the domain list from the file
+$domainList = Get-Content -Path $domainListFile
+
+# Create a new rule
+$parameters = @{
+    'Name' = $ruleName;
+    'FromScope' = 'InOrganization';
+    'SenderAddressLocation' = 'Header'
+    'RecipientDomainIs' = $domainList;
+    'MessageTypeMatches' = 'AutoForward';
+    'RejectMessageEnhancedStatusCode' = '5.7.1'
+    'RejectMessageReasonText' = $rejectionReason;
+    'Priority' = 0;
+    'Mode' = 'Enforce'
+    'Enabled' = $true
+}
+New-TransportRule @parameters
+
+# End the Exchange Session
+Get-PSSession | Where-Object {$_.ComputerName -eq 'outlook.office365.com'} | Remove-PSSession