Deliverability Guides

Step-by-step troubleshooting and optimization tutorials — the same checks I run in paid audits, written so you can run them yourself. Real commands, real examples, no fluff. Disagree with something? Every guide has a discussion section at the end.

Email Authentication Statistics 2026: We Subscribed to 34 Brands and Read 217 Real Emails Data Study

Only 57% enforce p=reject; 100% of what reaches the inbox is aligned. DMARC policies, ESP infrastructure, and spam placement — from real mail, not DNS scans.

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Google Postmaster Tools v1 Is Gone: What v2 Shows Now (and What You've Lost) New

The reputation dashboards died with v1 in August 2026 — but Gmail still scores you. What's in v2, and the monitoring stack that replaces the lost scoreboard.

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SPF, DKIM, DMARC: Why Each One Exists (and How to Verify Yours)

Forty years of an arms race in DNS records — then the 20-minute audit: dig, Show original, and the alignment checks green checkmarks miss.

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Gmail Open Rate Dropped? A Step-by-Step Diagnostic Workflow

Don't change five things at once. Work through Postmaster → authentication → blacklists → what-changed, in order.

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Inbox Placement vs. Deliverability: Why "98% Delivered" Tells You Nothing

One metric you can measure, one you can't — and why seed lists don't close the gap. What to watch instead.

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DMARC Aggregate Reports: What They Tell You and What to Actually Do

A real Google report, field by field — auth results vs alignment, three failure patterns, and a three-day path from p=none to reject.

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Domain Reputation: How Gmail Scores You, and How to Climb Back

What Bad/Low/Medium/High actually mean for your open rate, and the recovery strategy that fits each level.

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Prefer the theory applied to real data?

The case notes show these same principles on real Google Postmaster curves — an eight-week recovery, two relapses, and four months of boring, healthy High.