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Diffrence between TarpitInterval & MaxAcknowledgementDelay RRS feed

  • Question

  • We are having Exchange 2010 Environment. I want to understand the difference between TarpitInterval & MaxAcknowledgementDelay.

    On our receive connector TarpitInterval is set to 5 seconds & MaxAcknowledgementDelay is set to 30 seconds.

    While tracing SMTP logs I found following for different emails, what is the meaning of it?

    Tarpit for '0.00:00:01.622' due to 'DelayedAck',Delivered
    Tarpit for '0.00:00:04.180' due to 'DelayedAck',Delivered
    Tarpit for '0.00:00:26.520' due to 'DelayedAck',Delivered

    If TarpitInterval is set to 5 then why it is showing 26 seconds tarpit in above example logs (3rd one which is in bold)

    Thanks in advance.


    Monday, September 16, 2019 5:15 PM

All replies

  • Hello,

    We are having Exchange 2010 Environment. I want to understand the difference between TarpitInterval & MaxAcknowledgementDelay.

    On our receive connector TarpitInterval is set to 5 seconds & MaxAcknowledgementDelay is set to 30 seconds.

    While tracing SMTP logs I found following for different emails, what is the meaning of it?

    Tarpit for '0.00:00:01.622' due to 'DelayedAck',Delivered
    Tarpit for '0.00:00:04.180' due to 'DelayedAck',Delivered
    Tarpit for '0.00:00:26.520' due to 'DelayedAck',Delivered

    If TarpitInterval is set to 5 then why it is showing 26 seconds tarpit in above example logs (3rd one which is in bold)

    Thanks in advance.

    Monday, September 16, 2019 12:07 PM
  • Hi,

    Since you have asked the same question in our forum, we help you merge them together.

    Based on my knowledge, TarpitInterval sets the pause time for your Exchange server. That means your Exchange server will delay an SMTP response for 5 seconds (the default value) to a remote server. 

    MaxAcknowledgementDelay means the max time period Exchange transport server used to delay issuing an acknowledgement until it verifies that the message has been successfully delivered to all recipients.   

    "Tarpit for '0.00:00:26.520' due to 'DelayedAck',Delivered" in the log means the Exchange server waits about 26 seconds to issues an acknowledgement. It doesn't equal to the period of time used to delay an SMTP response.

    You can check this for more information about these parameters: Set-ReceiveConnector

    Regards,

    Lydia Zhou


    Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.

    Tuesday, September 17, 2019 2:42 AM
    Moderator
  • Thanks much Lydia.

    So these 26 seconds we can correlate to MaxAcknowledgementDelay setting but We have also set Tarpitinterval to 5 secs & I never see anything in SMTP log where my SMTP relay server waits for 5 seconds to response before data command send by the client.

    The communication between my relay server & remote SMTP host is happening over TLS & I have allowed the remote host's IP address in allowed list on my relay server's receive connector.

    So do you have any idea why the tarpit setting of 5 does not work here.

    Thanks in advance.


    Thursday, September 19, 2019 11:17 AM
  • Based on my research, tarpitting only makes sense on Receive Connectors exposed to the Internet. So Tarpitinterval should work with the receive connector used to receive emails from the Internet.

    Regards,

    Lydia Zhou


    Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.

    Tuesday, September 24, 2019 8:14 AM
    Moderator
  • Just checking in to see if above information was helpful. If you have any questions or need further help on this issue, please feel free to post back.

    Regards,

    Lydia Zhou


    Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.

    Tuesday, October 1, 2019 1:04 AM
    Moderator