Comment by sam_lowry_
11 hours ago
> Every email carries two "from" addresses
I made a presentation about exactly the same subject many years ago, but I was not shy of separating the SMTP protocol (RFC 821 and the following ) and the email message (RFC 822 and the following).
It makes the link between SPF, DKIM and DMARC much clearer.
Anyway. The article covers just the bare minimum, and in the most obscure way.
For those interested in the inner workings of contemporary email delivery... I recommend the posts by Alex Shakhov on LinkedIn https://www.linkedin.com/in/alexshakhov/ (Yes, there is still meaningful content on LinkedIn, it's just vanishingly rare)
If only I could read those articles without joining LinkedIn.
Are those posts available without logging in? This sounds like good stuff but I can’t access it.
I think he reposts them on his consulting page https://www.sh.consulting/blog and no, I am not affiliated. Just keeping an eye on the email deliverability topic as a hoppy.
I'm sure I don't speak just for myself when I ask, can you link the presentation?
I can't share all of it, but to understand the relationship between SPF, DKIM and DMARC one should know that DMARC covers two possible cases. Either DKIM domain must match From: domain or MAIL FROM domain must match the From: domain plus the IP address of the sender should pass the SPF check
https://mikhailian.mova.org/delivering-mails/1.png shows the SMTP plaintext chat for the first case,
https://mikhailian.mova.org/delivering-mails/2.png shows the second.