Test-Mailflow cmdlet

The Test-Mailflow cmdlet can be used to diagnose whether mail can be successfully sent and delivered. To send a test probe message to the administrator's email address, use the following command:
Test-Mailflow -TargetEmailAddress shakir.hussain@mstechguru.ae

Exchange Management Shell

If everything is working correctly, a new message will appear in the test user's mailbox:

This will help you in troubleshooting mail flow related issues.