How to increase the security of TLS in MailMarshal


This article applies to:

  • Trustwave MailMarshal (SEG) supported versions
  • See additional version-specific changes in notes

Question:

  • How do I increase the security of my TLS connections with SEG/MailMarshal?
  • How do I increase the encryption level of my TLS connections?

Response:

SEG allows you to select a preferred level of encryption for TLS connections. 
You can set the minimum cipher strength to LOW, MEDIUM or HIGH as per business requirements.
  • High strength includes only the newest and most secure cipher suites, usually with 256 bit encryption
  • Medium strength also includes many cipher suites with 128 bit encryption, and excludes older and less secure cipher suites
  • Insecure Compatibility strength (known as Low strength in versions below 8.0) includes older and less secure cipher suites  
Note that this is a minimum setting (the stronger ciphers will always be available and attempted first).

To set this option, see the TLS properties:
  • Outbound Security (TLS), in SEG Properties (Trustwave SEG Properties, Sender Properties section)
  • Inbound Security (TLS), in the properties of each processing node (Mail Servers > [select a server] > Server Properties

SEG also allows you to specify the protocol (SSL or TLS version) required for the connection. Refer to

  • Article Q19541: Specify the protocol to use with TLS 

Recommendations:

Trustwave recommends you evaluate these options based on organizational requirements.

However a minimum of Medium strength combined with high version level protocol would be recommended to ensure security. Lower strength ciphers are no longer considered to be secure.

  • The "low" option has been renamed "Insecure Compatibility" to reflect that these ciphers should not be used, unless absolutely required.

Notes:

Using the latest released version of MailMarshal is always recommended to provide the best security.

Last Modified 9/25/2023.
https://support.trustwave.com/kb/KnowledgebaseArticle14317.aspx