Guides & fixes

Every guide follows the same discipline: diagnose first, fix in order, prove it worked, and a ladder if it still fails.

Email authentication & deliverability

Outlook · Microsoft 365 · DMARC 550 5.7.515 / 5.7.509 “Access denied” — the complete DMARC fix

Two look-alike errors, one ordered cure: diagnose, SPF, DKIM, DMARC — with the exact Microsoft 365 records and the proof step at the end.

Shopify · Deliverability · DNS Shopify emails going to spam — the sender-domain authentication fix

Every CNAME from your own Shopify modal, one DMARC record, and the per-host gotcha for GoDaddy, Cloudflare and Namecheap — without touching your apex SPF.

SPF · DNS SPF PermError — too many DNS lookups

Count your record term by term, evict the dead tools, and stay under the limit of 10 for good.

In production

Moving DMARC from p=none to p=reject safely · Klaviyo + Cloudflare DKIM alignment.