Re: [perpass] Fwd: New Version Notification for draft-fenton-smtp-require-tls-01.txt

Yakov Shafranovich <yakov@shaftek.biz> Thu, 18 February 2016 03:47 UTC

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From: Yakov Shafranovich <yakov@shaftek.biz>
Date: Wed, 17 Feb 2016 22:47:07 -0500
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To: Jim Fenton <fenton@bluepopcorn.net>
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Subject: Re: [perpass] Fwd: New Version Notification for draft-fenton-smtp-require-tls-01.txt
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On Wed, Feb 17, 2016 at 10:42 PM, Jim Fenton <fenton@bluepopcorn.net>; wrote:
> On 2/17/16 2:13 PM, Yakov Shafranovich wrote:
>>
>> Section 3.4 - delivery:
>> It is unclear what "delivery" means here, especially considering that
>> SMTP may relay messages to another server, perhaps reference RFC 5598?
>> Also, the parts in section 1 and the optional parameter in section 2
>> should play together with this, perhaps by requiring TLS in IMAP, etc.
>> or not. Either way, this may need clarification.
>
> I have been trying to void "boiling the ocean" by constraining this
> feature to SMTP. From the context, it should be clear that by delivery I
> was referring to protocols such as IMAP and POP, although webmail
> applies here as well. Are you suggesting that this requirement should be
> a MUST rather than the SHOULD I proposed?
>>

Maybe a MUST for SMTP relays following this one, and SHOULD for non-SMTP?


>>
>> One other comment - perhaps some sort of limiting digital signatures
>> for headers only like DKIM can be employed by the receiving MTA to
>> certify that the receipt and transmission was effective? I am thinking
>> along the lines of Received headers or DKIM headers, which would allow
>> traceability.
>
> This seems to be a separate feature - authenticated return receipts.
> This might be useful, but I don't think it belongs here.  I would hope
> that MTAs would add information about REQUIRETLS to their Received:
> header fields, much as they do about the use of TLS for messages they
> receive, but I haven't worked out quite how to specify that yet.

+1 on the received headers.

Thanks