How-to
📬 Get into the inbox: authentication, hygiene, and warm-up
If your email lands in spam, nothing else matters. Authenticate your domain, honor the current Gmail/Yahoo bulk-sender rules, and keep your spam rate under 0.3% (aim under 0.1%).
🎯 Why it matters
Deliverability is the invisible foundation of email marketing: a great campaign in the spam folder earns nothing. Gmail and Yahoo's bulk-sender rules (for senders at 5,000+ messages/day) require SPF, DKIM, and DMARC, one-click unsubscribe, and a Postmaster spam-complaint rate under 0.3%. AI can order your fix list from your current setup; you confirm the current rules and your Postmaster numbers.
💬 My take
Land in the inbox, not the spam folder
The best email in the spam folder earns nothing. AI can read your sender setup and order the fixes; you confirm the current Gmail/Yahoo rules and pull your real complaint rate from Google Postmaster Tools, because those numbers are yours and the rules change.
Fastest path: one prompt, end to end
🤖 AI prompt — paste into ChatGPT / Claude
You are an email deliverability specialist.
My setup (paste what you have): sending domain, ESP [Klaviyo/etc], SPF/DKIM/DMARC status [set/unset/unknown],
one-click unsubscribe [on/off], Google Postmaster spam rate [%], list age/hygiene [describe].
Do this:
1. Open Google's current bulk-sender guidelines (support.google.com/a/answer/81126) and confirm today's requirements, do not rely on memory.
2. Return an ORDERED fix list (most damaging first) mapped to my setup, each with the exact place to fix it in Klaviyo.
3. Flag anything that violates the under-0.3% spam-rate rule or the authentication rules as urgent.
Do not guess or estimate any number. Every figure must come from the guidelines page or a number I gave you, and you must name the source next to it. Do not invent my Postmaster numbers; if I didn't give them, leave them blank and tell me to pull them. If you can't browse, say so, then order the list from what I gave you and tell me to confirm the current thresholds.
Output: ordered fix list + urgent flags.
Or do it in 5 steps
- Authenticate the domain: set SPF, DKIM, and DMARC, all three, aligned. In Klaviyo this is the "dedicated sending domain" setup, a DNS-records step. Use a DKIM key of at least 1024 bits (2048 recommended per Google), and DMARC can start at p=none as long as it's present and aligned. Without authentication, bulk senders route you to spam by default.
- Turn on one-click unsubscribe (the List-Unsubscribe and List-Unsubscribe-Post headers, plus a visible link in the body). Klaviyo adds these automatically on a verified domain, confirm it's active. It's a hard requirement now, not optional.
- Keep spam complaints under 0.3% in Google Postmaster Tools, the hard threshold, and aim under 0.1%, Google's recommended target. A spike means your content or list is the problem.
- Warm up a new domain by ramping volume over 2-4 weeks rather than blasting your whole list on day one.
- Run a sunset policy: stop mailing 180-day non-openers. Emailing dead addresses drags your sender reputation down for everyone.
Worked example (labeled): at 50,000 sends, the 0.3% cap is 150 complaints; the 0.1% target is 50. If you're seeing 200, you're over the hard line, pause, tighten segmentation to engaged users, and re-check Postmaster before your next send.
Check Postmaster weekly; re-verify authentication after any domain change.
⚖️ Do & Don't
Do
- Set up SPF, DKIM, and DMARC — all three, aligned — before you send at any real volume
- Keep spam complaints under 0.1%, and treat 0.3% as a line you never cross
- Add one-click unsubscribe (List-Unsubscribe headers) and honor it within 2 days
- Suppress unengaged subscribers (no opens/clicks in 6 months) at least monthly
Avoid
- Don't launch a new sending domain by blasting your full list — warm up gradually over 2-4 weeks
- Don't treat "some authentication" as good enough — a DMARC record without aligned DKIM still fails bulk-sender checks
- Don't keep mailing disengaged segments at full frequency just because they haven't unsubscribed
- Don't expect a fast fix after a reputation hit — recovery takes weeks of clean sending, not a config change
💡 Quick tips
- Move your DMARC policy from p=none toward p=reject in stages, watching reports at each step — jumping straight to reject can silently block legitimate mail
- If deliverability suddenly drops, pause your least-engaged segment first before touching anything else — it's usually the fastest lever
🏢 Brand in focus
BrandSubscribers +55% YoY, Klaviyo revenue 2x+ YoY, placed-order rate +50%+ YoY
Klaviyo customer case study · Why it fits: with a list in the millions, Huda Beauty still saw click-through sink and deliverability erode, the classic sign that volume without hygiene is a liability, not an asset. What it did well: scrubbed inactive contacts and moved to engagement-tiered sending, mailing recently-engaged subscribers most often and pulling back on the rest, "cleaning up a lot of the deliverability issues" in the CRM lead's own words. Watch out: the write-up is Klaviyo's own promotional case study, several changes (content refresh, automations) landed around the same time so segmentation alone isn't proven to be the whole story, and the metrics are brand-reported, not independently audited.
🏷️ Tags
emaildeliverabilityauthentication
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