Inbound emails through the Symantec Messaging Gateway (SMG) appliance fail with error message "All recipients are invalid". It fails to accept the inbound mails for certain recipient domains.
The Message Audit Logs contain the following error and the mail is rejected, although the "Recipient Validation" function is not active.
The recipient ( "rcpt to") domains are not configured as local domains.
Configure the local domain from Control Center via Protocols -> Domains.