vouch.fast · live SMTP verification
Bounces quietly wreck your sender reputation, and every dead address is money spent emailing no one. Vouch catches the fake, dead and risky ones before you hit send — so what you send reaches real people, and your domain stays trusted.
GET /v1/[email protected] · docs
$ curl -s https://vouch.fast/v1/[email protected] \ -H "Authorization: Bearer vch_live_••••••••"
{"status": "deliverable","reason": "mailbox_exists","score": 97,"checks": { "syntax": true, "domainHasMx": true,"smtpConnected": true, "mailboxExists": true,"catchAll": false },"flags": { "disposable": false, "roleAccount": false },"didYouMean": null,"meta": { "durationMs": 842 }}
$ Try it
Pick an address. Watch the real probe.
Type any address and watch Vouch decide whether it's safe to send to — the same live check that runs behind every API call. No email is sent, the address you type is never stored, and no account is needed.
or watch
Limited to a few checks a minute. Need more? Get an API key or read the docs.
How it works
Five gates. One verdict.
Five checks stand between a questionable address and your send button. The bad ones get caught early — often before we even touch the network — so only the real ones ever make it through.
01
Syntax
RFC-grade parse, IDN domains normalized. Garbage stops here — no network spent.
parseEmail()02
MX lookup
Mail hosts resolved and cached, priority-ordered. No records → undeliverable.
resolveMailHosts()03
SMTP probe
EHLO, MAIL FROM, RCPT TO against the real MX. Never DATA, always QUIT.
RCPT TO04
Catch-all
A second RCPT to a random local-part on the same connection. Accept-everything domains get caught.
random local-part05
Verdict
Signals map through one deterministic table to status, reason and score.
score 0–100deliverable · 97
What you get
Signals, not guesses.
Everything you need to keep bad addresses out of your database and rescue the good ones your customers mistype — in one response you wire straight into your signup flow.
RCPT TO → 250Live SMTP handshake
You learn a mailbox is real from the one source that truly knows — the mail server itself. No stale lists, no guessing, no bounces you could have prevented.
"catchAll": trueCatch-all detection
Some domains say yes to everything, then bounce it later. Vouch spots them and flags the address risky — so 'accepted' actually means it'll land.
"flags": { "disposable": true }Disposable, role & free flags
Keep burner signups and shared info@ inboxes out of your funnel — or wave them through. Vouch flags them; the call stays yours.
"didYouMean": "[email protected]"Typo rescue
A customer who types gamil.com is a customer you'd never reach. Vouch hands back the fix, so you can catch it in the form and keep the signup.
POST /v1/batchesBulk CSV & Excel
Hand us a messy list, get back a clean one — duplicates dropped, every address graded. Walk into your next campaign knowing it'll land.
Per-step receipts
Every verdict shows its work — so you can trust it, log it, and build your own rules on top.
syntaxtruedomainHasMxtruesmtpConnectedtruemailboxExiststruecatchAllfalse
5s step · 8s budgetFast enough for your signup form
Answers in about a second, even when a mail server drags its feet — quick enough to run right inside your signup flow without making anyone wait.
Four verdicts you can branch on
deliverableMailbox confirmed over SMTP. Send.riskyCatch-all, role account or greylisted. Deliverable, with an asterisk.undeliverableBad syntax, no MX, or the server said 550. Don't burn the bounce.unknownTimeouts or connection trouble. Retry later — don't guess.
score — one number that says how safe an address is to send to, 0–100.
MCP server
Your AI assistant can vouch too.
One config block gives Claude, Cursor, Cline — any MCP client — a verify_emailtool backed by the same live-SMTP engine behind this page. Ask “is this address real?” and your assistant checks with the mail server itself.
One tool: verify_email
Paste the config, drop in your API key, done — your assistant picks up a verify_email tool and answers with the full verdict, typo fixes included.
- Runs on your machine. npx fetches it on first use; your key is sent only to the Vouch API over HTTPS.
- The full verdict. Status, score, per-step checks, flags and didYouMean — the same response the REST API returns.
- Built for agents. Gate signups, clean lists or rescue typos mid-conversation — 1 credit per verification, like every call.
{"mcpServers": {"vouch": {"command": "npx","args": ["-y", "@datapad-nl/vouch-mcp"],"env": { "VOUCH_API_KEY": "vch_live_••••••••" }}}}
# or one command in Claude Code:$ claude mcp add vouch --env VOUCH_API_KEY=vch_live_•••••••• \ -- npx -y @datapad-nl/vouch-mcp
Pricing
Credit-based. Pay only for what you verify.
One credit verifies one address — buy any amount, and the more you buy the less each costs. Bulk uploads draw from the same balance, and de-duplication means you never pay to check the same address twice. Credits never expire.
free tier · 250 credits on signup · no card required
→At 50,000 credits you save 17% on the whole order.
🔒 Secured by Stripe · sign in to complete · taxes calculated at checkout
Need more than 1,000,000 credits or custom volume pricing? [email protected]
FAQ
Questions, answered.
What Vouch checks, what each verdict means, and how it stays fast.
How does Vouch verify an email without sending one?
Vouch opens a live SMTP conversation with the recipient's mail server and issues a RCPT TO command — the same step a real send uses to check whether a mailbox exists — then quits. It never transmits a message body (DATA), so no email is ever delivered.
What do the four verdicts mean?
deliverable means the mailbox was confirmed over SMTP. risky means it accepts mail but with a caveat — a catch-all domain, a role account, or greylisting. undeliverable means bad syntax, no MX records, or a 550 rejection. unknown means a timeout or connection problem, so you should retry rather than guess.
Can Vouch detect catch-all domains?
Yes. After the first RCPT TO, Vouch sends a second one to a random, almost-certainly-nonexistent local-part on the same connection. If the server accepts that too, the domain accepts everything — so the address comes back risky rather than deliverable.
How fast is a verification?
Most verifications return in about a second. Each step has a five-second timeout and the whole probe is capped at an eight-second budget, MX lookups are cached, and at most three mail hosts are tried — so Vouch fails fast when a server is unresponsive.
How is Vouch different from a regex check or a disposable-domain list?
A regex only proves an address is well-formed, and static lists go stale the moment a domain changes. Vouch checks the live server — it resolves current MX records and asks the actual mailbox whether it exists — then flags disposable, role and free-provider addresses on top. You get evidence, not a guess.
Can I try Vouch without an account?
Yes. The Try it box on this page runs the exact same pipeline the API does — live MX lookup, live SMTP handshake, catch-all probe — against any address you type, no sign-up needed. It's limited to a few checks per minute, and the address you type is never stored. For real volume, sign in and generate an API key.
Is there a free tier?
Yes. Every new account starts with 250 free credits the moment it's created — no credit card required. One credit verifies one address, so that's 250 real SMTP verifications through the API, the dashboard or a bulk upload. When you need more, credits are pay-as-you-go and never expire.
Can I verify a whole list at once?
Yes. Upload a CSV or Excel (.xlsx) file in the dashboard, or POST it to /v1/batches with your API key. Vouch scans every cell, removes duplicate addresses, and verifies each unique one in parallel, then gives you a downloadable results CSV. Because duplicates are removed before verification, you’re only charged for unique addresses.