This article applies to:

• Trustwave MailMarshal (SEG) 

Question:

• How can I adjust the behavior of MailMarshal SMTP Receiver checking "Where sender's name is/is not a fully qualified domain name"?

Procedure:

The MailMarshal SMTP Receiver rule condition "Where sender's name is/is not a fully qualified domain name" allows you to take action based on the server name that a remote server provides as part of the HELO SMTP command.

By default this condition has the following settings:

• Minimum 3 domain parts
• Maximum 10 domain parts

For instance, the following are not valid FQDNs by default:

• mailserver
• mailserver.com
• mailserver.some.very.long.set.of.sub.domains.at.an.ISP.somewhere.com

To configure these settings:

• In MailMarshal 10.0 and above, open the Management Console and navigate to Advanced Settings. Add one or more of these values:
  • Name: Receiver.HELOCheckMinSubDomains: The minimum number of domain parts required. 
  • Name: Receiver.HELOCheckMaxSubDomains: The maximum number of domain parts allowed. 
  • Type: Integer
  • Value: The desired minimum or maximum
• In MailMarshal 8.X and below, open the Registry Editor on the Array Manager. Within the base registry key, navigate to \Default\Receiver
  • In version 8.X: HKEY_LOCAL_MACHINE\SOFTWARE\Trustwave\Secure Email Gateway\Default\Receiver
  • For information about the registry location for each version, see article Q10832.
  • Enter one or both of the following DWORD values. Use Decimal entry to avoid confusion.
    • HELOCheckMinSubDomains: The minimum number of domain parts required. 
    • HELOCheckMaxSubDomains: The maximum number of domain parts allowed. 
• Save your registry settings or configuration settings.
• Commit the configuration changes and restart the MailMarshal Receiver service on each node.

Warning: Using the Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Trustwave cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Make sure that you back up your Registry prior to making any changes.

Notes:

• Some well known ISPs use FQDNs with at least 6 parts.