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Mails suddenly stuck on ESA

BWCBWC Cybersecurity Overlord ✭✭✭

Hi all,

for any reason since yesterday my ESA (10.0.6) stopped delivering mails properly, outbound mails got stuck in the queue with the following reason, e.g.

Timed out, status = ETIMEDOUT while connecting from ( to (

On the firewall I can see that the ESA is reaching the destination server on the internet, it's no connectivity issue though. Sometimes the mails are going through after a while, but mostly they are stuck. Sometimes a manual force delivery succedes but not always. All kinds of remote servers are affected, no pattern visible.

No changes were made on my end and I'am somewhat confused.


Category: Email Security Appliances


  • David WDavid W SonicWall Employee

    Were there any kind of alerts at the time?

    Was inbound email working correctly?

    The error you show from the MTA normally means there was no answer from the remote side.

    This could be due to the firewall, ISP or an outage at the remote side.

    Were the main ones involved using the same ISP?

    David Wilbur

     Technical Support Senior Advisor, Premier Services , SME Email Security

  • BWCBWC Cybersecurity Overlord ✭✭✭
    edited September 2020

    Hi @David W

    inbound mail is working fine AFAIK, the packet monitor on the firewall shows that the transfer suddenly stops and the last packet is an ACK from the remote side, no further packets form the ESA.

    All kind of remote ISPs are involved, I don't suspect the problem on the remote side.

    No alerts on the ESA.

    UPDATE: The ESA sends 2 minutes after the last ACK from the remote side another ACK, the remote side sends back an ACK, than another 2 minute wait and ESA sends an ACK again. This is where the timeout happens because both parties no longer talking to each other.


  • David WDavid W SonicWall Employee

    Sometimes we do see an issue where the NAT policy on the firewall stops working correctly and turning it off then on again addresses the issue.

    If you didn't have any inbound issues and there were no alerts it does not appear to be an issue with the Email security itself.

    If you see this start up again I would open a case and see if the tech can assist in seeing where the issue is.

    Without seeing it at the time it is occuring it can be very difficult to make any determination of the problem and would mostly be speculation.

    David Wilbur

     Technical Support Senior Advisor, Premier Services , SME Email Security

  • BWCBWC Cybersecurity Overlord ✭✭✭

    Will check with the Firewall again, working "forever" and now this made me wonder.


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