Exchange Server 2019 Transport service stuck in starting state

Hi Lasker Sokia

Thank you for reaching out to Microsoft Q&A forum

Based on your description, I understand that on your Exchange Server 2019, the Microsoft Exchange Transport service is failing to start and remains stuck in a "Starting" state indefinitely. Attempts to restart the service via PowerShell (Restart-Service MSExchangeTransport) or reboot the server have no effect.

As far as I know, this issue usually happens when the transport modules take too long to start, often due to problems with the queue database (mail.que) or folder permissions. The Transport service needs quick access to this database for mail routing, so delays caused by insufficient permissions, corrupted queue files, or Active Directory connection issues can prevent it from starting properly. Other services may run fine, but the Transport service is more sensitive to these dependencies, especially after updates or configuration changes. If not fixed, it can temporarily disrupt mail flow—though messages in the queue are typically preserved.

Therefore, you can follow the steps below to see if the issue can be solved:

Step 1: Create a backup

Back up C:\Program Files\Microsoft\Exchange Server\V15\TransportRoles\data\Queue. Check Event Viewer (Application → MSExchangeTransport) for Event IDs: 1022, 2080, 4000, 9646, or 1026.

Step 2: Enable diagnostics and verify permissions

Set-EventLogLevel "MSExchangeTransport\SmtpReceive" -Level Expert
Set-EventLogLevel "MSExchangeTransport\Categorizer" -Level Expert
icacls "C:\Program Files\Microsoft\Exchange Server\V15\TransportRoles\data\Queue" /grant "NETWORK SERVICE:(OI)(CI)F" /T

Step 3: Stop services and force terminate if needed

Stop-Service MSExchangeFrontEndTransport, MSExchangeDelivery, MSExchangeTransport -Force
# If hung:
$pid = (Get-Process EdgeTransport -ErrorAction SilentlyContinue).Idif ($pid) { Stop-Process -Id $pid -Force }

Step 4: Recreate Queue Database and Restart

cd "C:\Program Files\Microsoft\Exchange Server\V15\TransportRoles\data\Queue"
Rename-Item mail.que, trn.chk, trn.log -NewName {$_.Name + ".old"}
Remove-Item trntmp.log -ErrorAction SilentlyContinueStart-Service 
MSExchangeTransportTest-ServiceHealth

Step 5: Reset Logging and run System Checks (If Needed)

Set-EventLogLevel "MSExchangeTransport\SmtpReceive" -Level Lowest
Set-EventLogLevel "MSExchangeTransport\Categorizer" -Level Lowest
# Only if logs show .NET/corruption errors:
sfc /scannowDISM /Online /Cleanup-Image /RestoreHealth

Please feel free to leave a comment below if you require any additional help. 

Best regards

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