Hi I ran "get-healthreport" and got an unhealthy "Frontend Transport". I found out the problem is the monitor "OnPremisesSmtpClientSubmissionMonitor". I found this event: The client submission probe failed 3 times over 15 min
FrontendTransport health set unhealthy (OnPremisesSmtpClientSubmissionMonitor) - The client submission probe failed 3 times over 15 minutes. Seems like these alerts have started comming for some of the servers, where mailbox and CAS role is installe