This article applies to:

• Trustwave MailMarshal (SEG) 

Issue:

• The Local User Part of email addresses is limited to 64 characters according to Internet RFC (See RFC 5322, Section 4.5.3.1.1)
• The Domain Part of email addresses is limited to 255 characters according to Internet RFC (See RFC 5322, Section 4.5.3.1.2)
• The entire email address is limited to 254 characters according to Internet RFC
• However, experience shows that a significant number of legitimate messages generated by other software providers violate this standard by setting the local part to more than 64 characters
• MailMarshal does not take any action on non-complying addresses by default.

Enforcing the limit:

• You can enforce the limit at the MailMarshal Receiver using the Registry entry described in this article.
  • When enforced, long addresses are rejected at the Receiver with a message: 553 MAIL FROM: mailbox name too long

Note: This setting ENABLES the length check which is DISABLED by default.

• In MailMarshal 10.0 and above, open the Management Console and navigate to Advanced Settings. Add a new value:
  • Name: Receiver.EnforceLocalUserLengthCheck
  • Type: Boolean
  • Value: True (selected)
• 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 the value as a new DWORD value named EnforceLocalUserLengthCheck with value 1 (true).
• Save your registry settings or configuration settings.
• Commit the configuration changes and restart the MailMarshal Receiver service on each node.

As always, take due care when editing the Registry. Trustwave recommends that you make a backup before applying any changes.