How to set up DMARC and DKIM for MailchimpMailchimp sends your campaigns from its own servers, so by default the DKIM signature says d=mailchimp.com and the SPF check uses a Return-Path on mailchimp.com. Both checks pass — but for Mailchimp'sJul 23 · 5 min readcannypigeons.hashnode.dev
DNS drift: why email authentication decaysEmail authentication is configured in DNS, and DNS is a shared surface: your IT team, your web agency, your marketing tools, your registrar — and, if you're unlucky, an attacker — can all change it. TJul 23 · 5 min readcannypigeons.hashnode.dev
Source IPs in DMARC reports, explainedEvery row of a DMARC aggregate report starts with an IP address, a message count, and one question: is this server mine? The IP itself carries more evidence than most people expect. Reverse DNS, geoloJul 23 · 6 min readcannypigeons.hashnode.dev
What is an ESP — and why does it fail DMARC?An ESP (Email Service Provider) is any platform that sends email on your behalf: Mailchimp for newsletters, SendGrid or Mailgun for transactional mail, HubSpot or Klaviyo for marketing, Zendesk for suJul 23 · 3 min readcannypigeons.hashnode.dev
What is ARC?Forwarding is authentication's blind spot: a forwarded message arrives from an IP that fails SPF, and mailing lists that tag subjects or add footers break DKIM too. ARC — Authenticated Received Chain Jul 23 · 3 min readcannypigeons.hashnode.dev
