Email provider

DKIM setup for Mailgun

DKIM proves message integrity. Mailgun gives you a selector and key or CNAME targets — publish them exactly.

Common mistake: Using the sandbox domain for production — SPF/DKIM must be on the domain you send from.

Step by step

Step 1 Mailgun Control Panel → Sending → Domain settings → select your domain.

Step 2 Copy the exact hostnames and values Mailgun shows — do not invent selectors. Typical pattern:

TXT at k1._domainkey (or the selector Mailgun displays) with the public key value from the control panel.

Step 3 Add TXT or CNAME at the DNS provider that hosts your domain. Truncated keys fail verification.

Step 4 Query the record from an authoritative resolver or use propagation checker.

Step 5 Google Workspace / some hosts require clicking “enable” after DNS is green.

Step 6 Send a test message; check DKIM-Signature and d=. Run DNS Preflight. Align with DMARC: /fix/dmarc/.

DNS Preflight — verify SPF, DKIM, DMARC in one pass.

DMARC alignment — fixes when reports show failures.

In the provider’s domain authentication / sender settings — copy live values.

Use what the provider specifies — both are common.

Wrong selector, truncated key, or signing not enabled after publish.

You need SPF + DKIM alignment for your From domain — DKIM is often the easier path for ESPs.

DNS Preflight for the published key; send test mail for header verification.