How Mailing Lists Break DMARC, and Why ARC Only Partly Fixes It

This story was originally published on HackerNoon at: https://hackernoon.com/how-mailing-lists-break-dmarc-and-why-arc-only-partly-fixes-it. Why mailing lists break DMARC, what ARC (RFC 8617) actually does about it, why it only helps where the receiver trusts the sealer, and why From-munging is the reliable fix. Check more stories related to cybersecurity at: https://hackernoon.com/c/cybersecurity. You can also check exclusive content about #email-authentication, #dmarc, #dkim, #mailing-list-management, #email-deliverability, #dmarc-alignment, #mailing-lists-vs-dmarc, #mailing-list-security, and more. This story was written by: @vadimivanov. Learn more about this writer by checking @vadimivanov's about page, and for more stories, please visit hackernoon.com. Mailing lists break DMARC because they modify messages and forward from their own servers. ARC lets a list vouch that the message passed DMARC before it touched it, but only helps at receivers that evaluate it and trust the sealer's reputation. From-munging is the universal fix; run both.