Resend domain stuck verifying: red wavy underlines on the domain details page

Symptom: domain stays unverified hours after you added the DNS records.

1. Confirm the cause: open the domain details page in the Resend dashboard. Resend validates your DNS in real time and draws red wavy underlines under records with errors, so start there instead of guessing.
2. Check the checklist: every record from the domain's Records tab is present, each is at the correct location (records usually live under the send subdomain, not the root domain), and values match what Resend generated exactly.
3. Watch for the record-set change: older domains show a TXT plus an MX record for SPF and both must be right for SPF to verify at all. Domains created after August 2026 may show CNAME records instead.
4. Do not delete and re-add the domain as a first move; that resets the records Resend expects. Fix the flagged records in place.
5. Verify: after correcting records, use the "Restart verification" button in the dashboard to trigger a fresh check, and watch the underlines clear. Domains usually verify within 15 minutes once records are right.

Documented in Resend knowledge base: domain verification usually completes within 15 minutes; the domain details page does real-time DNS validation with red wavy underlines on bad records; records must be at the correct location (the send subdomain) with exact values; older domains need TXT+MX both correct for SPF, newer ones may use CNAMEs. Evidence: resend.com/docs/knowledge-base/what-if-my-domain-is-not-verifying.