The 2026 email deliverability checklist
SPF, DKIM, DMARC, one-click unsubscribe, engagement hygiene and the Gmail/Yahoo bulk-sender rules — a plain-English checklist to keep your email landing.
Inbox providers tightened the rules and never loosened them. Here's the short, current checklist — no jargon, no folklore.
1. Authenticate everything
SPF, DKIM and a DMARC policy are table stakes. If you send from your own domain, all three must pass. Most spam filtering starts by asking: did this mail really come from who it claims?
2. Honour one-click unsubscribe
The RFC 8058 header pair is now expected for bulk mail. An unsubscribe should be one click, honoured instantly, and applied across every list the address belongs to — not a login-gated preference maze.
3. Keep complaint rates low
Gmail's bulk-sender guidance draws a hard line around a 0.3% complaint rate. Stay well under it by mailing people who asked, suppressing bounces immediately, and never buying lists.
4. Warm up, don't blast
A brand-new domain sending 50,000 emails on day one looks exactly like a spammer. Ramp volume gradually — here's how.
5. Align your links
Links in your email should live on your sending domain. Mismatched tracking domains are a classic filter trigger.
6. Watch engagement, prune the dead
Providers read opens and clicks as trust signals. Sunset addresses that haven't engaged in months rather than dragging your reputation down with them.
Solstral does most of this for you automatically — see why we treat deliverability as a product feature.