Guides

SPF, DKIM, and DMARC guides

Practical notes on the DNS records behind a sending domain. Written for the person who edits the zone, or who has to tell that person what to publish. A DNS check is not an inbox-placement test. The sample shows what a Snapshot report looks like.

• Set up DMARC for a Shopify sending domain

  Shopify’s CNAME records, one _dmarc TXT, and when to leave p=none.

• Fix an SPF PermError from too many DNS lookups

  What counts toward the 10-lookup limit, and why flattening goes stale.

• Why emails land in spam: SPF, DKIM, and DMARC

  Authentication failures, From-domain alignment, and the Gmail and Yahoo bulk-sender rules.

• How to read a DMARC aggregate XML report

  How rua XML is built, and how to tell spoofing from a sender you forgot to authenticate.