Exchange 2016 Mail Flow is Not Working

At this point, the most helpful next steps are to verify that all Exchange services are running, check that the Transport service starts without errors, confirm that your send/receive connectors still exist and haven’t lost their configuration, and make sure the server’s TLS certificate is valid and properly bound. It’s also important to review the event logs (Transport, MSExchangeFrontEndTransport, MSExchangeIS) for any configuration or authentication errors. If major components are corrupted, the safest and most reliable fix is usually to run a “setup /m:recoverserver” using the same Exchange build as the backup, which rebuilds the server roles without touching the databases. Given the age of the backup and hybrid dependencies, this recovery step often repairs the underlying issues faster than continuing to patch individual symptoms.

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