When I examined the receive connector logs to identify the problem with the mail traffic I was experiencing on one of my Exchange servers, I saw that the error “
421 4.3.2 Service not available” was constantly repeated.
When I followed the mail flow in the log, I observed that the steps continued successfully, but at the last stage it gave the error “
421 4.3.2 Service not available“.
334 authentication response,
235 2.7.0 Authentication Successful,
Mail From : <…@…>,
421 4.3.2 Service not available,
I checked the
ServerComponentState of the server, and saw that the
To fix this situation, we need to use the following command.
Set-ServerComponentState ExchServerName -Component HubTransport -State Active -Requester Maintenance
Have a nice day !