Writing that delivers.
Deliverability guides and product notes — no filler.
SMTP response codes explained for email senders
A field guide to the SMTP response codes email verifiers read: 2xx, 4xx, and 5xx, what each means for deliverability, and the verdict each one produces.
Email bounce rate benchmarks: what's normal and what's not
The average email bounce rate is 2.33%, but normal varies by industry. Benchmarks by sector, how to calculate yours, and the fixes that actually lower it.
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.
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.
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.