Re: [ietf-smtp] Email explained from first principles
Sam Varshavchik <mrsam@courier-mta.com> Mon, 24 May 2021 22:06 UTC
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From: Sam Varshavchik <mrsam@courier-mta.com>
To: ietf-smtp@ietf.org
Date: Mon, 24 May 2021 18:06:29 -0400
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Subject: Re: [ietf-smtp] Email explained from first principles
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John Levine writes: > Mailing lists have been editing messages for 40 years, long before anyone > ever thought of DKIM or DMARC. It is a well known DMARC failure that it > doesn't work with mailing lists. s/that it doesn't work with mailing lists//. I'm struggling to identify some tangible value-added that DKIM/DMARC brings to the table. Ostensibly, these signatures prove that the mail really comes from the domain it purported to come from. Ok, that's cool, but what is the point? I'm told that this is to block spam that forges others domains. Splendid, but I can't help but notice that spam that makes it past my spam filters features a shiny signature more often than not. Here's a small sample from today's batch. I've masked the domain to avoid triggering someone's OCD's spam filter: DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d=[spam domain] [blah blah blah] From: "Mail-Admin courier-mta.com" <mailer-daemon@[spam domain]> To: mrsam@courier-mta.com And here's one more: DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; s=k1; d=[spam domain] [blah blah blah] DomainKey-Signature: a=rsa-sha1; c=nofws; q=dns; s=k1; d=[spam domain]; [two for the price of one] Subject: Strange Liver-Hormone Helps You Burn Fat 20 Hoursa Day It seems very obvious to me that DKIM/DMARC has been a complete failure, even ignoring mailing list-related breakage. They had some initial success, when they were a novelty. That changed as soon as their implementations gained some foothold. Spam senders figured out that spam filters are whitelisting signed domains. Therefore, all they have to do is use their own domain, sign their spam, and they's whitelisted! Pure comedy gold.
- [ietf-smtp] Email explained from first principles Kaspar Etter
- Re: [ietf-smtp] Email explained from first princi… Bron Gondwana
- Re: [ietf-smtp] Email explained from first princi… Alessandro Vesely
- Re: [ietf-smtp] Email explained from first princi… Viktor Dukhovni
- Re: [ietf-smtp] Email explained from first princi… Viktor Dukhovni
- Re: [ietf-smtp] Email explained from first princi… Kaspar Etter
- Re: [ietf-smtp] Email explained from first princi… Peter J. Holzer
- Re: [ietf-smtp] Email explained from first princi… John Levine
- Re: [ietf-smtp] Email explained from first princi… Sam Varshavchik
- Re: [ietf-smtp] DKIM and DMARC, Email explained f… John Levine
- Re: [ietf-smtp] Email explained from first princi… Dave Crocker
- Re: [ietf-smtp] DKIM and DMARC, Email explained f… Dave Crocker
- Re: [ietf-smtp] Email explained from first princi… John R Levine
- Re: [ietf-smtp] DKIM and DMARC, Email explained f… Sam Varshavchik
- Re: [ietf-smtp] DKIM and DMARC, Email explained f… John Levine
- Re: [ietf-smtp] DKIM and DMARC, Email explained f… Sam Varshavchik
- Re: [ietf-smtp] DKIM and DMARC, Email explained f… Dave Crocker
- Re: [ietf-smtp] DKIM and DMARC, Email explained f… Sam Varshavchik
- Re: [ietf-smtp] DKIM and DMARC, Email explained f… Dave Crocker
- Re: [ietf-smtp] DKIM and DMARC, Email explained f… Sam Varshavchik
- Re: [ietf-smtp] DKIM and DMARC, Email explained f… Dave Crocker
- Re: [ietf-smtp] DKIM and DMARC, Email explained f… Matthias Leisi
- Re: [ietf-smtp] DKIM and DMARC, Email explained f… Sam Varshavchik
- Re: [ietf-smtp] DKIM and DMARC, Email explained f… Dave Crocker
- Re: [ietf-smtp] DKIM and DMARC, Email explained f… John Levine
- Re: [ietf-smtp] DKIM and DMARC, Email explained f… Sam Varshavchik
- Re: [ietf-smtp] DKIM and DMARC, Email explained f… Nathaniel Borenstein
- Re: [ietf-smtp] DKIM and DMARC, Email explained f… John C Klensin
- Re: [ietf-smtp] Email explained from first princi… Kaspar Etter
- Re: [ietf-smtp] Email explained from first princi… John R Levine
- Re: [ietf-smtp] Email explained from first princi… John R Levine
- Re: [ietf-smtp] Email explained from first princi… Kaspar Etter
- Re: [ietf-smtp] Email explained from first princi… John R Levine
- Re: [ietf-smtp] Email explained from first princi… Richard Clayton
- Re: [ietf-smtp] Email explained from first princi… Alessandro Vesely
- Re: [ietf-smtp] Email explained from first princi… John C Klensin
- Re: [ietf-smtp] the point of domain authentication John R Levine
- Re: [ietf-smtp] mailing lists are complicated, wa… John Levine
- Re: [ietf-smtp] the point of domain authentication Sam Varshavchik
- Re: [ietf-smtp] the point of domain authentication John Levine
- Re: [ietf-smtp] mailing lists are complicated, wa… Alessandro Vesely
- Re: [ietf-smtp] mailing lists are complicated, wa… John R Levine
- Re: [ietf-smtp] mailing lists are complicated, wa… Dave Crocker
- Re: [ietf-smtp] Email explained from first princi… Richard Clayton
- Re: [ietf-smtp] mailing lists are complicated, wa… Alessandro Vesely