SSL/TLS and port 587

[Victor Duchovni]

On Tue, Jan 22, 2008 at 10:38:24AM -0800, Ed Gerck wrote:

> List,
> 
> I would like to address and request comments on the use of SSL/TLS and port 
> 587 for email security.
> 
> The often expressed idea that SSL/TLS and port 587 are somehow able to 
> prevent warrantless wiretapping and so on, or protect any private 
> communications, is IMO simply not supported by facts.

Nothing of the sort, TLS on port 587 protects replayable *authentication*
mechanisms, suchs as "PLAIN" and "LOGIN". It can also allow the client to
authenticate the server (X.509v3 cert) and preclude MITM attacks on
mail submission. I've not seen any reputable parties claiming that TLS
submission is protection against intercepts.

I maintain the TLS code for Postfix, the documentation does not anywhere
make such claims. However we do support TLS sensitive SASL mechanism
selection:

    http://www.postfix.org/postconf.5.html#smtpd_tls_auth_only
    http://www.postfix.org/postconf.5.html#smtp_sasl_tls_security_options

which is highly suggestive of using TLS to protect plain-text passwords
in flight.

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