How email verifiers work (SMTP RCPT in 60 lines of Node), and why they fail on 56% of startups
This story is from 2026-10-13. It is preserved in the archive; the latest stories are on the live feed.
Email verification tools mostly do one thing under the hood: they open an SMTP connection to the domain's mail server and ask whether a mailbox exists, then hang up before sending anything. Here is how that works, in about 60 lines of Node, and what happened when I ran it against 499 Y Combinator c…
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- 2026-10-13 08:35 · DEV Community — AI
How email verifiers work (SMTP RCPT in 60 lines of Node), and why they fail on 56% of startups