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Cannot send outgoing emails due to the reverse DNS lookup issue in InterScan Messaging Security Virtual Appliance (IMSVA)

    • Updated:
    • 31 Jan 2015
    • Product/Version:
    • InterScan Messaging Security Virtual Appliance 8.2
    • InterScan Messaging Security Virtual Appliance 8.5
    • InterScan Messaging Security Virtual Appliance 9.0
    • Platform:
    • N/A N/A
Summary
When there is an issue with the reverse DNS lookup for an internal MailServer connection, you are unable to send outgoing emails and any of the following error messages may appear:
  • For IMSVA:
    mail1 postfix/smtpd[23161]: disconnect from unknown
  • For Exchange Server queue:
    450-4-7-1-client-host-rejected-cannot-find-your-hostname
Details
Public

To resolve the issue, allow connection from internal servers:

  1. Make sure that the IP of the MailServer is added in the approved list for IP Filtering. From the console, go to IP Filtering > Approved List to check this.
  2. Back up /opt/trend/imss/postfix/etc/postfix/main.cf.
  3. Open /opt/trend/imss/postfix/etc/postfix/main.cf and look for the "smtpd_client_restrictions" key.
  4. Add the "permit_mynetworks" on the "smtpd_client_restrictions" key similar to:
    smtpd_client_restrictions = permit_mynetworks,
    hash:/opt/trend/imss/postfix/etc/postfix/NRSAllowAccessList {...Other original values}
    (permit_mynetworks has to be the first value in the list)
  5. Restart Postfix. Check this Postfix readme file for more details about Postfix. Follow the instruction for mynetworks_style (default: subnet).
Premium
Internal
Rating:
Category:
Configure; Troubleshoot
Solution Id:
1099295
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