Users receive Mailbox appears to be offline message

Users receive the following message while accessing OWA

"Your mailbox appears to be offline, Try to access it again in 10 seconds"

To test that the Exchange services are running correctly, run the following cmdlet using the Exchange Management Shell on the CAS:

Test-ServiceHealth

The results will show all services not started populated under ServicesNotRunning. Under each Exchange role, check to see if RequiredServicesRunning is False

To restart the services, enter the following cmdlet using the Exchange Management Shell:

Test-ServiceHealth | Select ServicesNotRunning | foreach { Start-Service $_.ServicesNotRunning }