Notes on deliverability, from the trenches.

DKIM Jul 24, 2026 · 6 min read

DKIM Keys: 1024 vs 2048 Bits, and When to Rotate Them

In 2012, a mathematician named Zachary Harris got a curious recruiting email from Google and noticed something better than the job: Google was signing its...

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BLACKLISTS Jul 24, 2026 · 6 min read

How to Get Off an Email Blacklist: The Complete Removal Guide

A bounce message mentions Spamhaus, a monitoring alert flags a listing, or your open rate just fell off a cliff and a scan confirms the reason. The instinct...

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DELIVERABILITY Jul 24, 2026 · 6 min read

Why Your Emails Go to Spam (and How to Diagnose It)

Search this question and you'll find listicles: "17 reasons your emails go to spam." They're not wrong, they're useless. Seventeen possible causes with no...

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DMARC Jul 24, 2026 · 6 min read

How to Read a DMARC Report: Decoding the Aggregate XML (With Examples)

You published a DMARC record with a rua= address, and now your inbox fills up with attachments named things like google.com!yourdomain.com!1753...xml.gz....

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DMARC Jul 24, 2026 · 5 min read

Moving DMARC from p=none to p=reject Without Breaking Your Email (2026 Guide)

p=none satisfies Google and Yahoo's bulk sender requirement. It also protects you from exactly nothing: anyone can still spoof your domain, and receivers...

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DELIVERABILITY Jul 24, 2026 · 5 min read

Google & Yahoo Sender Requirements in 2026: The Complete Compliance Guide

In February 2024, Google and Yahoo turned email authentication best practices into hard requirements. Two years later, the grace period is over: enforcement...

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SPF Jul 24, 2026 · 5 min read

The SPF 10 DNS Lookup Limit: Why It Silently Breaks Your Email (and How to Fix It)

Your SPF record can be syntactically perfect, list every service you send from, and still fail on every single email you send. No bounce, no error in your...

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