Re: [Trans] CT for opportunistic STARTTLS in SMTP

I don't see the relevance of CT to opportunistic STARTTLS.

Opportunistic STARTTLS is a feature of the sender whereby the sender picks STARTTLS if offered, but otherwise will send the email.  If the alternative was send unprotected over plain TCP, you may as well negotiate TLS if offered.  Moreover, if TLS negotiation fails for whatever reason, the send remembers the fact and done not attempt to negotiate next time. 

The sender does have a list of SMTP domains where it requires TLS authentication, but that is mandatory  STARTTLS. 

-----Original Message-----
From: Trans [mailto:trans-bounces@ietf.org] On Behalf Of Paul Hoffman
Sent: Tuesday, February 25, 2014 9:54 AM
To: Ben Laurie
Cc: trans@ietf.org; Daniel Kahn Gillmor
Subject: Re: [Trans] CT for opportunistic STARTTLS in SMTP

On Feb 25, 2014, at 9:36 AM, Ben Laurie <benl@google.com> wrote:

>> At the earlier CT meeting, I think someone proposed that there could be a check that the cert was in actual use at the place it said it was.
> 
> That does not seem effective to me.

It is more effective than doing nothing; it may not be effective enough to prevent overwhelm by spam. I was just pointing it out as something that was proposed, not well-thought-out.

--Paul Hoffman
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