Public/Exchange/Protection/Examples/Block-Inbound-Sender-Domain.json

{
    "Name": "Block inbound from blocked-sender.example",
    "Comments": "Reject inbound mail from a specific external sender domain at the gateway. Replace blocked-sender.example with the actual domain to block. Review and adjust the transport rule priority after creation so it fits your existing mail flow rules.",
    "Mode": "Enforce",
    "Enabled": true,
    "FromScope": "NotInOrganization",
    "SentToScope": "InOrganization",
    "SenderDomainIs": ["blocked-sender.example"],
    "RejectMessageReasonText": "Mail from this sender domain is not accepted by this organization.",
    "RejectMessageEnhancedStatusCode": "5.7.1",
    "StopRuleProcessing": true
}