https://nobounce.dev/blog/ How email validation actually behaves against live DNS: typo correction, RFC 7505 null MX, the SERVFAIL/NXDOMAIN split, and failing open in a signup flow. en Mon, 24 Aug 2026 00:00:00 GMT https://nobounce.dev/ https://nobounce.dev/ Email validation that suggests the correction instead of only rejecting. Mon, 24 Aug 2026 00:00:00 GMT https://nobounce.dev/blog/fail-open-email-validation-signup/ https://nobounce.dev/blog/fail-open-email-validation-signup/ Treat the validator as advisory infrastructure: set a timeout, branch on the verdict, record what was actually checked, and let users through when it cannot answer. Mon, 24 Aug 2026 00:00:00 GMT https://nobounce.dev/blog/batch-validate-email-list/ https://nobounce.dev/blog/batch-validate-email-list/ POST /v1/check/batch returns one verdict per address keyed by email_sha256; chunk oversized lists, check remaining quota first, and act on suggestions instead of only counting rejects. Mon, 24 Aug 2026 00:00:00 GMT https://nobounce.dev/blog/choosing-an-email-validation-api/ https://nobounce.dev/blog/choosing-an-email-validation-api/ Accuracy percentages on vendor pages are unfalsifiable, so evaluate the response contract, the failure behaviour and the retention policy instead. Mon, 24 Aug 2026 00:00:00 GMT https://nobounce.dev/blog/mx-validation-misses-typo-domains/ https://nobounce.dev/blog/mx-validation-misses-typo-domains/ An MX lookup accepts the four most common Gmail and Hotmail misspellings, because typo domains are registered and resolve correctly. Mon, 24 Aug 2026 00:00:00 GMT https://nobounce.dev/blog/null-mx-rfc-7505-reserved-domains/ https://nobounce.dev/blog/null-mx-rfc-7505-reserved-domains/ A domain publishing MX 0 . is telling you it accepts no mail at all, and example.com does the same — but breaking your test suite is not the same problem as a bad signup. Mon, 24 Aug 2026 00:00:00 GMT https://nobounce.dev/blog/typosquat-mx-host-clustering/ https://nobounce.dev/blog/typosquat-mx-host-clustering/ Typo domains are an unenumerable long tail, but the operators collecting mail for them reuse infrastructure, so the MX host is the tractable signal. Mon, 24 Aug 2026 00:00:00 GMT https://nobounce.dev/blog/servfail-vs-nxdomain-email-validation/ https://nobounce.dev/blog/servfail-vs-nxdomain-email-validation/ A resolver failure and a nonexistent domain arrive as different DNS status codes and demand opposite responses: fail open on one, reject on the other. Mon, 24 Aug 2026 00:00:00 GMT https://nobounce.dev/blog/suggest-the-correction-not-rejection/ https://nobounce.dev/blog/suggest-the-correction-not-rejection/ Rejecting a mistyped address ends the session; naming the intended address recovers it, which means the interesting engineering is in the suggestion. Mon, 24 Aug 2026 00:00:00 GMT https://nobounce.dev/blog/validate-emails-from-an-agent/ https://nobounce.dev/blog/validate-emails-from-an-agent/ An autonomous agent can obtain access, validate an address and recover from an error without a human in the loop, provided every step is a single HTTP request. Mon, 24 Aug 2026 00:00:00 GMT https://nobounce.dev/blog/why-no-smtp-rcpt-probing/ https://nobounce.dev/blog/why-no-smtp-rcpt-probing/ The technique that promises per-mailbox certainty depends on infrastructure reputation, returns weak signals at the largest providers, and is permanently outside this product's scope. Mon, 24 Aug 2026 00:00:00 GMT