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Re: [ietf-dkim] draft-ietf-dkim-ssp-02.txt Discardable/Exclusive

2008-02-21 01:24:13
How very strange I wonder what explains the over 2k bounce messages of 
undeliverability due to content in my honey trap mail account that has been 
spoofed in the last 3 days alone. It appears that cheap software, designer 
shoes and On line degrees don't apply to the RFC's. It seems that organizations 
around the world don't adhere to the specs. That is why commercial messages 
need to be delivered to the inbox in some other method from edge to edge than 
smtp via a community service bureau or other entity. This WOULD allow a 99.999% 
delivery rate of valid messages while killing 99.999% of spam. Also it would 
free up considerable bandwith as commercial mail would only need one copy of a 
message to be delivered to each ISP instead of spraying millions hoping for a 
high receive rate. 
thanks,
Bill


-----Original Message-----
From: ietf-dkim-bounces(_at_)mipassoc(_dot_)org on behalf of Thom O'Connor
Sent: Wed 2/20/2008 7:43 PM
To: ietf-dkim(_at_)mipassoc(_dot_)org
Subject: Re: [ietf-dkim] draft-ietf-dkim-ssp-02.txt Discardable/Exclusive
 
Eric Allman wrote:
I am in no way married to the word DISCARDABLE.  We used it in SSP-02 
because it matched ASP.

It has occurred to me that we've spent FAR too much time arguing 
about exactly what word to use.  I'm deeply tempted to switch to 
numbers, special characters, or random gibberish strings so that 
people have to read the actual description.

Hi Eric,

I understand this sentiment, and your point here is notable.

However, it is very important that the terminology in use here is 
accurate and appropriate. The global messaging user-base wants and 
expects guidance on implementation that should be clear and direct. The 
truth of the matter is, the discarding of email should be expressly 
discouraged. No message should ever be discarded - RFC 2821 suggests 
this though does not explicitly disallow or discourage it:

http://www.ietf.org/rfc/rfc2821.txt
Delivery SMTP systems MAY reject ("bounce") such messages rather than deliver 
them.

The discarding of email is one of the key causes of some significant 
loss of trust in email as a reliable means of communication. While it 
may be argued that spam may have caused email receiving domains to react 
in this way as a defense mechanism, it is actually the overreaction - 
perhaps due to a lack of guidance - that has allowed providers to think 
that discarding messages is a satisfactory response to the spam or 
malware threat. Perhaps, if our techniques were 100% accurate in 
ensuring that no valid message was ever lost, discarding could be 
appropriate. These techniques will not likely ever reach 100% accuracy.

If we (where "we" is the email industry here that seeks to maintain and 
even expand the usefulness of email itself, rather than seeing our users 
resort to making a phone call or using IM when they need a "sure" method 
of communication) should be clear about this then, one appropriate value 
for the SSP record would be "reject" or something equally directive, 
perhaps "verify". And if we are to really seek to be clear on the 
Signing Practice in use, then perhaps we may even include a "none" value:

none - The domain signs no email.
unknown - The domain may sign none, some, or all email.
all - All mail from the domain is signed with an Author Signature.
reject (or verify) - All mail from the domain is signed with an Author
          Signature.  Furthermore, if a message arrives without a valid
          Author Signature due to modification in transit, submission via
          a path without access to a signing key, or other reason, the
          domain encourages the recipient(s) to reject it if it does not
          verify.

There are certainly valid reasons that a domain may request this higher 
level of requested interpretation - signature-based verification moves 
email towards an (optional) higher level of reliability and identity 
verification with legal and commercial implications.

Douglas Otis wrote:
Agreed.  This changes "strict" (the exclusivity) assertion into
something that does not express a domain's intentions on
exclusivity.  This assertion simply increases the likelihood of
having the domain's messages discarded.

Using Hector's term "exclusive"-

exclusive:
All mail from the domain is signed with an intent to avoid
agents that may damage or remove signatures.  Furthermore,
in lieu of a trusted third-party signature, if a message
arrives without a valid Author Signature due to
modification in transit, submission via a path without
access to a signing key, or other reason, the domain
encourages the recipient(s) to reject the message or issue
a DSN when the RFC 2821 MAILFROM domains match.

This line of thinking is on target, though we really need to get better 
at using words our users will understand. "exclusive" is ambiguous, and 
I would argue, not an easily understood concept. "Signature did not 
verify" would seem to be an error message that could possibly be 
understood by a normal user in a DSN message.

Sincerely, respectfully,
-thom
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