KB ID 0000267
Event ID 7518
Sender Id must be configured with a list of trusted mail servers before it can be enabled
You have enabled Sender ID filtering on your “Virtual SMTP Server.” Like so,
You need to add your internal IP range and the PUBLIC ip address of the Exchange server.
1. Open Exchange System Manager > Global Settings > Message Delivery > Right Click > Properties > General > Add > Add.
2. Add in your local IP scope AND the public IP of the Exchange Server > OK.
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