Blog
The email verification blog.
Long-form technical writing on how verification actually works, what the results mean, and where the standard approach falls short. Written by the person who runs the lists.
Email Verification API: A Developer's Guide
What to evaluate in any verification API, then a worked integration with auth, bulk jobs, webhooks and backoff.
Read the articleHow to Clean a 100,000-Email List the Right Way
What cleaning at scale actually involves, what it costs at live pack prices, and what to do with each segment.
Read the articleHow to Verify an Email Address Without Sending Mail
The SMTP conversation that answers the question, why doing it yourself breaks at scale, and what to do instead.
Read the articleWhy Single-Engine Verifiers Fail at Catch-All Domains
The SMTP conversation that makes catch-all mailboxes unfalsifiable in a single probe.
Read the articleCold Email Bounce Rate: What's Normal, What's Not
Where the thresholds come from, what drives variance between lists, and how to sit comfortably under them.
Read the articleEmail Verification Accuracy: What 99% Really Means
Headline accuracy figures are measured on the addresses that were never in doubt. Here is the metric that is not.
Read the articleHow to Reduce Your Email Bounce Rate to Under 2%
The four levers that control bounce rate, with verification given the depth it usually does not get.
Read the articleWhat Is Email Verification? A Complete Guide
How verification works stage by stage, where it fails, and what each result actually tells you.
Read the articleSingle-Engine vs Two-Pass Email Verification
Why one SMTP pass leaves a quarter of a B2B list unresolved, and what a second pass does about it.
Read the articleWhat Is a Catch-All Email Address?
The domain configuration that accepts mail for every address, why it breaks verification, and how to resolve it.
Read the articleNew articles are added regularly. Subscribe by RSS.
Verify a list while you read.
100 free credits on signup, no card required.