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Writing that delivers.

Deliverability guides and product notes — no filler.

The eight-stage verification pipeline drawn as a narrowing funnel of checks
EngineeringFebruary 4, 2026

How email verification works: the 8 stages

A stage-by-stage look at how email verification works, from syntax to the SMTP mailbox probe — what each check can prove, and what it can't.

A verification list where every address is accepted, flagged with an amber catch-all badge
GuidesJanuary 28, 2026

What is a catch-all email? The honest guide

Catch-all domains accept mail for any address, so no verifier can confirm a mailbox exists. What that means, why tools disagree, and how to send safely.

A bar chart of bounce rate climbing past a dashed 2% warning threshold
DeliverabilityJanuary 22, 2026

Why bounce rate is the metric mailbox providers actually watch

Hard bounces are the loudest reputation signal you send. Here's how providers read them, and the thresholds to stay under.