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starttls_injection_policy — protect against SMTP injections prior to TLS


Starttls_Injection_Policy = "allow|ignore|reject"


This option deals with the security issue described by CVE-2011-0411, namely that SMTP commands can be injected before the MTA switches to TLS. Consequently, a "man in the middle" could inject SMTP commands that are not protected by TLS.

This option can be set to the following:

  • allow – The ESMTP listener will process commands after STARTTLS and before successful SSL negotiation.

  • ignore – Any commands after STARTTLS are ignored, and commands after the successful TLS negotiation will be interpreted.

  • reject – If any commands are present in the buffer immediately after a STARTTLS command, the STARTTLS is rejected and the connection is dropped. This event will be logged in the rejectlog.

The default value is reject.


starttls_injection_policy is valid in the ESMTP_Listener, listen, pathway, pathway_group and peer scopes.

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