The 15-point email deliverability checklist for 2026

Print this and put it on the wall. Every box you can tick raises inbox placement; every blank one is a specific place your email might be silently disappearing.

Authentication (do these before anything else)

1. SPF record — TXT at domain root, lists authorized senders, ends in ~all or -all.
2. DKIM record — TXT at selector._domainkey.yourdomain.com, published by your provider.
3. DMARC record — TXT at _dmarc.yourdomain.com, start at p=none, upgrade weekly.
4. MX records — even if you don't receive email at the sending domain, publish a reasonable MX record; some receivers penalize domains with none.

Sending patterns

5. Consistent volume — cold domains that suddenly send 10k messages get throttled. Warm up over 14 days.
6. No dormant lists — never mail an address that hasn't opened in 12+ months. They're now spam-trap candidates.
7. Handle bounces automatically — hard bounces off the list on first attempt, soft bounces after three consecutive.
8. Process complaints instantly — Gmail spam-button reports arrive via feedback loop; suppress the address the same day.

Content signals

9. Subject matches body — Gmail scores mismatch. "Order confirmed" subject with a promotional body earns Promotions filing.
10. One clear CTA — 8+ links, 40% images, and no plain-text version reads as promotional.
11. Include plain-text version — every HTML email should have a plain-text alternative; providers weight this.
12. Reasonable image ratio — 60/40 text-to-image or better. Image-heavy emails get filtered.

Infrastructure

13. Separate reputation for transactional vs marketing — use different subdomains (mail.yourbrand.com vs news.yourbrand.com) or different IPs.
14. List-Unsubscribe header — mandatory for bulk since Feb 2024. Include both mailto: and one-click POST variants.
15. Monitor bounce/complaint rate weekly — bounces > 5% or complaints > 0.1% triggers throttling. Catch it early.

Run this quarterly

Deliverability decays. Recipients change addresses, forget who you are, mark you as spam. Run this checklist quarterly and treat it as maintenance, not a one-time setup.