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YHC
YHC
Explorer
October 21, 2023
Question

lost connection while receiving the initial server greeting

  • October 21, 2023
  • 7 replies
  • 5463 views

Dear All,

 

We have troubles sending email to a specific mail domain with the following error message:

lost connection with mgw.ntu.edu.tw[140.112.8.25] while receiving the initial server greeting

 

This error happened after we adjusted our Fortigate 30E policy but we have no problems sending emails to other addresses.  Could anyone advise us what kind of policy issues could results in this error?  Or does it simply because of network/connection issues?

 

Thank you.

7 replies

dbu
Staff
dbu
Staff
October 21, 2023

Hi @YHC ,
If you have FortiMail try to increase the greeting timeout. The default value is 30 seconds.

 As per RFC 2821 , is  recommended a timeout value of 5 minutes (300 seconds).  Of course you can adjust it lower. 

 

From CLI:
config system mailserver
   set timeout-greeting <seconds_int>
end

https://docs.fortinet.com/document/fortimail/7.2.2/cli-reference/59838/system-mailserver

    YHC
    YHCAuthor
    Explorer
    October 23, 2023

    Hi,

     

    Thank you.

    Unfortunately, I am not using FortiMail.

    I found that the SMTP transaction time is pretty long (more than 15 sec.).

    Could it be the cause of lost connection?

     

    I am wondering if there anything wrong with our FortiGate 30E setting and results in our  long SMTP transaction time.

    Could anyone advise?

    Thank you.

    dbu
    Staff
    dbu
    Staff
    December 24, 2023

    Yes it can be connection issue. You might have either delay or drops on the path. 
    From Fortigate side i believe there is no timeout option to configure to extend the delay. 

    Is it possible to check something similar from the Email server side? 

     

      Elija
      Elija
      Visitor III
      October 21, 2023

      I too got the same issue

      AEK
      SuperUser
      AEK
      SuperUser
      December 24, 2023

      Hello

      You can use mxtoolbox.com to check connection time and transaction time of your remote mail gateway (use "Test Email Server" menu).

      If the result is good than it is also possible that your FGT's pub IP is simply blocked from mail gateway side. You need to ask mail administrator to check it for you.

      AEK
      Sheikh
      Staff
      Sheikh
      Staff
      December 25, 2023

      Hello @YHC 

       

      Have you tried to get the packet capture on FortiGate ?

       

      diagnose sniffer packet any "140.112.8.25 and port XX" 4 0 l <----------change port number accordingly (25, 587,465 etc..).

      and reproduce the issue.

       

      regards,

       

      Sheikh

        AEK
        SuperUser
        AEK
        SuperUser
        January 13, 2024

        Can you give more details about the configuration the you changed?

        Check if your mail reputation is ok.

        Also check if you are not simply blocked by your recipient's gateway.

        AEK
        austinjhones72
        austinjhones72
        New Member
        January 13, 2024

        Experiencing email issues can be challenging. The 'lost connection' error may stem from Fortigate 30E policy adjustments or network challenges. Ensure the policy settings align with email server requirements. Verifying network connectivity globalfist and consulting Fortigate support might help resolve the specific domain sending problem.

        janefoster92
        janefoster92
        New Member
        February 21, 2024

        It sounds like the policy adjustments on your Fortigate 30E might have inadvertently affected the way your emails are routed or recognized by specific domains like mgw.ntu.edu.tw. It could be a misconfiguration that's causing these domains to not acknowledge your server's greeting. Checking your SMTP settings and ensuring they align with whatsgb guidelines for secure and reliable email communication might help.

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