Server 2019 / IIS SMTP Server - Email Stuck in Queue / Not Being ReleasedRSS

2 replies

Last post Nov 11, 2019 07:04 AM by Yuk Ding

  • Server 2019 / IIS SMTP Server - Email Stuck in Queue / Not Being Released

    Nov 08, 2019 06:13 PM|brendo234|LINK

    I've recently upgraded a number of servers from Windows 2008 R2 to Windows Server 2019. 2 of the servers require SMTP which I have installed on both, however, 1 server works as it should and the 2nd, the emails get stuck in the queue and don't ever get sent/released.

    I found this post (which I hoped would solve my problem, but it still persists): Windows Server 2019 built-in SMTP server: Emails stuck in queue and "The remote server did not respond to a connection attempt" in event log

    Upon viewing my Event Log, I found the following Warning messages for SMTPSVC: Message delivery to the host '' failed while delivering to the remote domain '' for the following reason: An SMTP protocol error occurred.

    I am able to send mail using the following PowerShell script, but email sent via .NET apps and websites is not being released. 

    Send-MailMessage -SMTPServer localhost -To -From -Subject "SMTP Test" -Body "Email test through PowerShell"

    Has anyone else dealt with SMTP issues on Windows Server 2019? Any thoughts or additional resources would be greatly appreciated.


    Sending mail through PowerShell continues to work, however, sending mail through ASP.NET webforms/apps seems to not connect. Running a Wireshark trace, there is no SMTP activity when mail is sent through .NET apps. My SMTP log is as follows, but there is no associated outbound SMTP traffic in the Wireshark trace, just an email added to the Queue folder:

    18:24:14 MAIL - 250

    18:24:14 RCPT - 250

    18:24:14 DATA - 250

    18:25:48 QUIT - 240

    The mail is generated, however it is just left in the Queue folder and never gets sent.

    Currently, the .NET apps are set to connect to localhost, I've tried updating this to as well with no luck.

    It seems that this is a Windows Server 2016/2019 problem from what I've been able to find. The post linked above seems to resolve the problem by putting SMTP service into delayed start mode, however that did not make a difference in my case.

    Any help or direction would be greatly appreciated.

  • Re: Server 2019 / IIS SMTP Server - Email Stuck in Queue / Not Being Released

    Nov 10, 2019 04:28 AM|administrator.|LINK

    It is very cleare that your server sittings are not proper

  • Re: Server 2019 / IIS SMTP Server - Email Stuck in Queue / Not Being Released

    Nov 11, 2019 07:04 AM|Yuk Ding|LINK

    Hi Brendo234,

    It is hard to provide solution. 

    Currently, the best way to troubleshooting this issue is capture a dump file and try to capture the exception. 

    If you have MS premier contract, you could involve premier engineer directly. They would help you analyze these dump files and try to find the root cause.  You may have to figure out the hanged method and let them check in which condition the queue would stuck.

    I'm afraid it is hard to provide solution from here since I'm not able to reproduce this issue on my side.

    Best Regards,

    Jokies Ding

    Yuk Ding

    MSDN Community Support
    Please remember to "Mark as Answer" the responses that resolved your issue.