The Email Verifier Built on a 9-Check Engine

Yes, and that is the entire job of an email verifier. Verifox opens a live SMTP conversation with the domain's mail server, asks it to accept the address exactly the way a real sending server would, reads the response, and disconnects before any message content moves. The mailbox owner never sees a thing.

The whole exchange takes about 380 ms at the median. The full method, check by check, is documented on the email verification service page.

Yes, with honest caps. The widget at the top of this page runs 4 verifications a day with no account and no card, so you can try the real engine before you commit to anything.

A free signup adds 1,000 credits immediately, or 2,500 when you register with a work address. Beyond that, credits are pay-as-you-go, never expire, and carry volume pricing localized to your region, so you only pay for the addresses you actually verify.

Nine checks run in parallel on every address: syntax and format validation (RFC 5321 and 5322), domain existence and MX presence, an SMTP handshake and mailbox-exists ping, a disposable-domain match, role-address detection, catch-all detection, an AI-confidence pass on catch-all hits, a domain age signal, and an SPF, DKIM, and DMARC authentication check.

Only when an address clears the whole stack does it come back valid. For a quick one-off look at a single address, the free email checker runs this exact engine behind a simpler page.

Risky means the mailbox could not be confirmed or ruled out with certainty, so we hand you the evidence instead of a coin flip. The usual causes: a catch-all domain that accepts every address during the handshake, a role inbox like info@ or sales@, a domain registered days ago, or missing SPF, DKIM, and DMARC records.

Every risky result ships with a confidence score and the per-check breakdown, so you can pick your own send-or-suppress threshold instead of inheriting ours.

You need more than an SMTP handshake, because a catch-all server says yes to every address, real or invented. Verifox layers an AI-confidence pass on top: it weighs the domain's age, authentication posture, and naming patterns to score how likely that specific mailbox actually exists.

That layer is the one most free tools skip, and it matters: 20 to 40% of B2B email lists sit behind catch-all domains. Catch-all resolution is where this verifier earns its accuracy number.

99.99% on our 1,000-address benchmark list, measured in-house and including the catch-all cases most tools mark unknown. The engine has verified 2.1B+ emails to date.

Free and paid run the identical pipeline. The free tier caps how many addresses you can verify, never how deeply each one gets checked, so the verdict on this page matches what the API returns for the same address.

CSV upload from the dashboard, or stream addresses straight through the REST API for anything programmatic. Bulk jobs process roughly 10,000 emails per minute on the standard tier, and every address in the file gets the full nine-check treatment with a per-address verdict and confidence score.

Your free signup credits cover small lists outright. For bigger ones, credit packs are pay-as-you-go and never expire.

No. Each address is verified in memory and discarded the instant the verdict returns. We never store, log, or sell what you paste here, on the free tier or any paid one.

Verifox is SOC 2 Type II certified, and the privacy policy spells out exactly what we touch and for how long. Short version: the address lives as long as the verification does.

In practice, nothing. People say “verify email address” and “validate email address” to mean the same job: confirm an address is real, reachable, and safe to send to. Verifox runs the identical nine-check engine either way.

If you prefer the validator phrasing, the free email validator is the same tool under a different name. Both share the same accuracy, the same verification engine, and the same free tier.

Yes. The REST API reference documents every endpoint, so you can drop real-time verification into signup forms, CRMs, or any tool that speaks REST. At a 380 ms median it fits inside a form submit, with 99.9% uptime on Starter and 99.99% on a Volume contract, live at status.verifox.ai.

Verifox also ships native MCP server support, so AI agents like Claude and Cursor can verify addresses without glue code. HubSpot, Salesforce, Zapier, Klaviyo, and Mailchimp connect out of the box as well.