Local User Part length check

This article applies to:

• Trustwave MailMarshal (SEG) 6.9 and above 

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
• MailMarshal 6.9 enforces this limit at the Receiver with a message such as: 553 MAIL FROM: mailbox name too long
  • 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 7.0 and above does not take any action on non-complying addresses by default.
• In version 7.0 and above, you can still enforce the limit at the MailMarshal Receiver using the Registry entry described in this article.

For MailMarshal 6.9 customers, the issue is resolved in version 7.1 which is publicly available. Customers are advised to upgrade to version 7.1+ to resolve this issue.

Setting:

The following Registry setting is available in version 7.0 and above.

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

1. On the Array Manager, edit the Registry (10.X: use Advanced Settings in the Management Console)
2. Navigate to the SEG Receiver key:
   • In version 8.X: HKEY_LOCAL_MACHINE\SOFTWARE\Trustwave\Secure Email Gateway\Default\Receiver
   • 10.X: value names have the prefix Receiver. (Receiver dot).
   • For full details of the location for each product version, see article Q10832.
3. Add or edit a DWORD value: EnforceLocalUserLengthCheck
4. Set the value to 1.
5. To apply the change, commit configuration.

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