← Friday, October 2, 2026Cloud & infraGuide

SPF authorizes senders, DKIM signs mail, and DMARC enforces alignment

mailfully.com 12 min read Editor score 6/10

The guide explains how SPF authorizes sending servers, DKIM signs messages and DMARC checks alignment and applies policy. These records are practical prerequisites for reliable automated email delivery.

What: SPF, DKIM, and DMARC are DNS-based email authentication mechanisms that work together to check a message and its sender.
How: SPF checks the sending server, DKIM verifies a signature, and DMARC checks alignment with the visible From address and applies policy.
Why it matters: Engineers sending automated email need these checks to reduce authentication failures that can keep messages from arriving.

A receiving server checks a message with SPF and DKIM, then uses their results for DMARC. Sketched from the article's own text.

Read on mailfully.com → Hacker News · 27 comments

Discussion

Discussion is not switched on yet. Use Note above to keep your own thoughts on this story.

Headline, summary, brief and diagram are written by a model from the source's own text; the link, byline and numbers come from the source. Read the original before relying on a claim.