001INPUT
Paste the address
Drop any email into the pill. Gmail, Outlook, custom domains, role aliases. Single address now, bulk CSV on signup.
Instant Deliverability Test
The Email Deliverability Tester That Tells You If Any Address Will Accept Mail.
Test any address against the MX, SMTP, and mailbox-state checks the receiving server runs, on the same 9-point engine our paid API uses. Know if it is deliverable or will bounce, with 99.99% accuracy. No signup, no card.
Trusted by 500,000+ leading GTM teams of all sizes
From paste to verdict
How the email deliverability tester works
Three steps, no signup, no card on file. Paste any address, watch the nine-check engine run the MX and SMTP deliverability test, read the verdict in two seconds.
002ENGINE
Run the 9-check engine
Nine checks fire in parallel. Syntax, DNS, SMTP, catch-all, disposable, role, age, auth, mailbox state. Verdict in about two seconds.
003VERDICT
Verdict in 2 seconds
Valid, invalid, or risky. Plus a confidence score, the per-check breakdown, and a recommended retry policy. Read on the page or via API.
The 9-point engine
Nine checks. One verdict.
The same nine-check engine our paid email verification API runs. Every email, every verification, every time.
- 01
Syntax
Every address runs a full RFC 5321 and RFC 5322 compliance pass before a single network call goes out. The engine catches what visual scanning misses, the double dot in
alice@verifox..ai, the trailing period, the IDN homograph that looks valid but resolves to a different domain.Bundled typo suggestions let your form offer “did you mean alice@gmail.com?” instead of rejecting silently.
- 02
Domain & MX
Once syntax passes, the engine resolves the domain. We confirm the DNS records exist, fetch the MX record priority list in order, and verify at least one mail-exchange server is actively accepting connections right now.
Misspelled domains like
gmial.com, expired domains, and parked-for-sale domains all fail this gate before the engine wastes a single SMTP roundtrip.
- 03
SMTP handshake
The engine opens a TCP connection on port 25, performs the EHLO handshake, then negotiates
MAIL FROMandRCPT TO. Every server response code (220, 250, 550, 552) is parsed deterministically against the IANA enhanced-status registry.This is the moment a mailbox proves it actually exists. No third-party guesses, no statistical heuristics, just the receiving server's own answer.
- 04
Catch-all detection
Some domains accept every email regardless of whether the mailbox exists, a setup known as a catch-all configuration. The engine sends a deterministic probe to a deliberately fake address (
zzz9k7q@domain.com); if the server returns the same 250 OK it returned for the real address, the domain is catch-all.The verdict isn't dropped, it's flagged RISKY so you know the deliverability signal is degraded.
- 05
Disposable
The engine maintains a curated registry of 10,247 disposable email providers, including Mailinator, Guerrilla Mail, 10MinuteMail, Tempmail, and the long tail of regional clones.
Any address matching the blocklist is flagged INVALID. Deliverability to a mailbox that exists for 10 minutes and is never checked is functionally zero, regardless of whether the SMTP handshake passes.
- 06
Role address
info@,support@,no-reply@,admin@,hello@,billing@,contact@. These are shared inboxes, not individuals.The engine extracts the local-part of every address, matches it against the known role-prefix registry, and tags the result with a reduced engagement score.
You don't drop them automatically. The verdict tells you they're roles so you can decide whether they belong in your outbound.
- 07
Domain age
Fresh-spam domains registered hours ago are the single biggest source of inbound abuse. The engine queries WHOIS and RDAP for every unique domain, extracts the registration date, and flags anything under 30 days old with a “fresh” warning.
Domains aged 5+ years pick up a corresponding trust signal. The same heuristic spam filters have been using since the early 2000s, ported into the verdict.
- 08
Email authentication
SPF, DKIM, and DMARC together prove the sender is authorised to send from that domain.
The engine reads each policy via DNS, validates SPF includes recursively, scans six common DKIM selectors for a published key, and confirms DMARC alignment with the
From:header.A failing DMARC policy means the sender can be spoofed, so the verdict warns you before you reply.
- 09
Mailbox state
Beyond “exists vs doesn't exist”, the engine extracts the precise mailbox state from the SMTP server's response. Full inbox (552 / 522 quota), disabled mailbox (550 5.1.1), out-of-office autoresponder, frozen account.
Each state maps to a specific retry policy. Full inbox retries in 6 hours. Disabled drops permanently. The verdict tells you which bucket the bounce belongs in so your retry logic doesn't waste cycles.
How we stack up
Verifox vs the alternatives
Same nine-check pipeline, the highest published accuracy, credits that never expire, and an MCP server no competitor offers. Head-to-head with the two providers our buyers shortlist.
| Feature | Verifox | NeverBounce | ZeroBounce |
|---|---|---|---|
| Published accuracy claim | 99.99% | 99.0% | 99.6% |
| Credits expire | Never | Yes | Never |
| Free credits on signup | 1,000–2,500 / one-time | 1,000 / monthly | 100 / monthly |
| Verify without signup | |||
| Catch-all resolution | AI confidence | Flagged only | AI scoring |
| Real-time API | |||
| Bulk CSV upload | |||
| MCP server for AI agents | |||
| SOC 2 + GDPR + CCPA |
What teams are saying
Built for the teams that ship outbound
Growth leads, marketers, and engineers running real campaigns on real lists. Specific numbers, specific tools they switched from, and a verified email address on every byline.
90% lower bill, 0.4% bounces
We were paying ZeroBounce a four-figure monthly bill and still landing 3% bounces on cold campaigns. Switched the pipeline to Verifox, dropped to 0.4% bounces, and cut the bill by more than 90%.
Thomas G.GTM Lead, Stripe
Catch-all finally has a verdict
Other tools flag 30% of our B2B list as 'risky catch-all' and leave the call to us. Verifox returns a real verdict on those addresses, with a confidence score. We send more, we send safer.
Brittany K.GTM Lead, HubSpot
Reputation rebuilt in 6 weeks
We had a Gmail spam-folder problem after a bad list import. Verifox cleaned the list and the warmup ran on the same engine. Back in primary inbox in six weeks. One vendor, half the cost.
Dale M.GTM Lead, Slack
0.7% bounce on 50k
Ran a 50,000-address outbound list through Verifox before our quarterly campaign. Bounces landed at 0.7%, sender reputation didn't move, replies were up 22% over last quarter.
Erica K.GTM Lead, Discord
MCP in 10 minutes
Their MCP server let me wire email verification directly into our internal Claude agent in about ten minutes. Zero glue code. No other vendor in this space has thought about that workflow.
Greg L.GTM Lead, OpenAI
10k/min held under 400ms
Tested Verifox at 10,000 verifications per minute on a Tuesday morning. Latency held under 400ms median, no soft failures, no rate-limit walls. The vendor we benched throttled at 2,000/min.
Rini V.Product Manager, Vercel
Hygiene that doesn't break pipeline
Our SDRs were enriching from three tools and 14% of the emails were invalid before they hit the sequencer. Verifox sits in the pipeline now and the team stopped seeing 'undeliverable' replies the next week.
Jonathan A.GTM Lead, MongoDB
Bulk that actually ships
Bulk upload, sorted CSV back in twenty minutes, plug into our growth stack. The half-day list-hygiene project per cohort turned into something the marketing intern runs on autopilot.
Emma F.GTM Lead, Linear
Scores you can act on
Verifox returns a 0-100 confidence score per address, not just a label. We thresholded at 75 for the cold sequencer, 60 for nurture, and our deliverability team finally has a knob they can tune.
David H.GTM Lead, Snowflake
90% lower bill, 0.4% bounces
We were paying ZeroBounce a four-figure monthly bill and still landing 3% bounces on cold campaigns. Switched the pipeline to Verifox, dropped to 0.4% bounces, and cut the bill by more than 90%.
Thomas G.GTM Lead, Stripe
Reputation rebuilt in 6 weeks
We had a Gmail spam-folder problem after a bad list import. Verifox cleaned the list and the warmup ran on the same engine. Back in primary inbox in six weeks. One vendor, half the cost.
Dale M.GTM Lead, Slack
MCP in 10 minutes
Their MCP server let me wire email verification directly into our internal Claude agent in about ten minutes. Zero glue code. No other vendor in this space has thought about that workflow.
Greg L.GTM Lead, OpenAI
Hygiene that doesn't break pipeline
Our SDRs were enriching from three tools and 14% of the emails were invalid before they hit the sequencer. Verifox sits in the pipeline now and the team stopped seeing 'undeliverable' replies the next week.
Jonathan A.GTM Lead, MongoDB
Scores you can act on
Verifox returns a 0-100 confidence score per address, not just a label. We thresholded at 75 for the cold sequencer, 60 for nurture, and our deliverability team finally has a knob they can tune.
David H.GTM Lead, Snowflake
Catch-all finally has a verdict
Other tools flag 30% of our B2B list as 'risky catch-all' and leave the call to us. Verifox returns a real verdict on those addresses, with a confidence score. We send more, we send safer.
Brittany K.GTM Lead, HubSpot
0.7% bounce on 50k
Ran a 50,000-address outbound list through Verifox before our quarterly campaign. Bounces landed at 0.7%, sender reputation didn't move, replies were up 22% over last quarter.
Erica K.GTM Lead, Discord
10k/min held under 400ms
Tested Verifox at 10,000 verifications per minute on a Tuesday morning. Latency held under 400ms median, no soft failures, no rate-limit walls. The vendor we benched throttled at 2,000/min.
Rini V.Product Manager, Vercel
Bulk that actually ships
Bulk upload, sorted CSV back in twenty minutes, plug into our growth stack. The half-day list-hygiene project per cohort turned into something the marketing intern runs on autopilot.
Emma F.GTM Lead, Linear
90% lower bill, 0.4% bounces
We were paying ZeroBounce a four-figure monthly bill and still landing 3% bounces on cold campaigns. Switched the pipeline to Verifox, dropped to 0.4% bounces, and cut the bill by more than 90%.
Thomas G.GTM Lead, Stripe
0.7% bounce on 50k
Ran a 50,000-address outbound list through Verifox before our quarterly campaign. Bounces landed at 0.7%, sender reputation didn't move, replies were up 22% over last quarter.
Erica K.GTM Lead, Discord
Hygiene that doesn't break pipeline
Our SDRs were enriching from three tools and 14% of the emails were invalid before they hit the sequencer. Verifox sits in the pipeline now and the team stopped seeing 'undeliverable' replies the next week.
Jonathan A.GTM Lead, MongoDB
Catch-all finally has a verdict
Other tools flag 30% of our B2B list as 'risky catch-all' and leave the call to us. Verifox returns a real verdict on those addresses, with a confidence score. We send more, we send safer.
Brittany K.GTM Lead, HubSpot
MCP in 10 minutes
Their MCP server let me wire email verification directly into our internal Claude agent in about ten minutes. Zero glue code. No other vendor in this space has thought about that workflow.
Greg L.GTM Lead, OpenAI
Bulk that actually ships
Bulk upload, sorted CSV back in twenty minutes, plug into our growth stack. The half-day list-hygiene project per cohort turned into something the marketing intern runs on autopilot.
Emma F.GTM Lead, Linear
Reputation rebuilt in 6 weeks
We had a Gmail spam-folder problem after a bad list import. Verifox cleaned the list and the warmup ran on the same engine. Back in primary inbox in six weeks. One vendor, half the cost.
Dale M.GTM Lead, Slack
10k/min held under 400ms
Tested Verifox at 10,000 verifications per minute on a Tuesday morning. Latency held under 400ms median, no soft failures, no rate-limit walls. The vendor we benched throttled at 2,000/min.
Rini V.Product Manager, Vercel
Scores you can act on
Verifox returns a 0-100 confidence score per address, not just a label. We thresholded at 75 for the cold sequencer, 60 for nurture, and our deliverability team finally has a knob they can tune.
David H.GTM Lead, Snowflake
Why this one
Deliverability testing, without the tradeoffs
Most free deliverability testers either stop at a syntax check or make you wait on a seed-list send. Ours runs the full nine-check pipeline the paid plans use to judge every address, capped only on volume.
Accuracy
99.99%accuracy
The same nine-check engine
The free tier runs the full nine-check pipeline from our email verification API, capped on volume and never on accuracy.
Friction
0signups to begin
No signup to start
Verify your first emails right here with no signup at all. Create a free account when you go past four checks a day.
Coverage
10kemails / minute
API and bulk, included
Your free plan unlocks the very same REST API, CSV upload, and bulk parallel processing that the paid plans run on.
Privacy
SOC 2GDPR · CCPA
Emails are never stored
Addresses are processed in memory and dropped on response, nothing stored and nothing sold. Read the privacy policy.
Address-level deliverability, explained
What it really means to test email deliverability
When people set out to test email deliverability, they usually mean one of two very different things. One is inbox placement: will a campaign land in the inbox, the Promotions tab, or spam, which depends on your sending domain, your content, and your reputation. The other, the one this tool is built for, is address-level deliverability: for a given address, will the receiving mail server accept a message at all, or is the mailbox dead and destined to bounce. Get the second wrong and the first never matters, because no amount of clever copy rescues a message sent to an address that does not exist.
Our deliverability tester answers that second question by running the same conversation a real mail server would. It resolves the domain's MX records, opens an SMTP handshake, and pings the specific mailbox, all without delivering anything. The result tells you whether the address is deliverable, undeliverable, or risky, and flags the awkward cases in between: catch-all domains that accept everything, disposable inboxes, and role aliases like info@ or support@ that often should not be mailed at all. That is the same engine behind our email verification API, so a free test on this page is not a watered-down preview.
The payoff is simple. A list scrubbed of undeliverable addresses keeps your hard-bounce rate low, and a low bounce rate is what protects the sender reputation every future send rides on. If your goal is squarely bounce prevention, the email bounce checker frames the identical engine around that outcome; to clean a whole list at once, the free email validator handles bulk uploads. Whichever door you come through, the deliverability verdict is the same, and credits scale with you as your volume grows.
Trust & compliance
Enterprise-grade security and scale
Every layer of the stack carries a third-party attestation, so you can ship into regulated industries without rebuilding your compliance posture.
SOC 2 Type II
Independently audited to the SOC 2 Type II standard.
GDPR
Built for the EU with full GDPR data-subject rights.
CCPA
California opt-out, do-not-sell, plus DSAR handling.
ISO 27001
Information security held to the ISO 27001 standard.
ISO 42001
AI governance aligned to the new ISO 42001 standard.
Common questions
Email deliverability, answered
The questions we get from teams that land here to test email deliverability before a send, with the real numbers, real limits, and real opinions behind our verification stack.
Is the email deliverability tester actually free?
Yes. You can test 4 addresses per day for deliverability from this page without an account. No card, no signup.
Create a free account and you get 1,000 tests on the spot, or 2,500 if your signup email is a work address. After that, credits are pay-as-you-go and never expire on any paid plan, with volume pricing shown for your region.
What does this email deliverability test actually check?
It tests the deliverability signals that live on the address itself, the same things the receiving mail server cares about when it decides whether to accept your message. Nine checks run in parallel every time you test an address:
- Syntax + format validation (RFC 5321 / 5322)
- Domain existence and MX record presence
- SMTP handshake and mailbox-exists ping
- Disposable-domain match
- Role-address detection
- Catch-all domain detection
- AI-confidence pass on catch-all addresses
The MX + SMTP pair is the heart of the deliverability check: it confirms the domain can receive mail and that the specific mailbox is live, so you know an address is deliverable before you send. If you just want to check one email at a time, the checker runs the very same engine.
Does this test inbox placement or spam score?
No, and that is on purpose. This tool tests address-level deliverability: whether a mailbox exists, is live, and will accept mail, or whether it is dead and will bounce. It does not run a seed-list send, score your message content, or report which folder you land in.
Inbox placement and spam scoring are a different job that depends on your sending domain, your reputation, and the message itself. Cleaning out undeliverable addresses first is the foundation that makes the rest of your deliverability work pay off, because a list full of dead mailboxes drags down every send regardless of how good the content is.
How does testing tell me whether an address will bounce?
A bounce is just the receiving server telling you, after the fact, that an address is dead. The deliverability test runs the exact MX lookup and SMTP handshake that server would, without delivering anything, so you get that verdict before the send instead of as a failure report after.
Addresses come back as deliverable, undeliverable, or risky with a confidence score. If your angle is specifically bounce prevention on a send, the email bounce checker frames the same engine around hard-bounce risk.
How accurate is the deliverability test?
Same engine as the paid plans. 99.99 % accuracy on a 1,000-address benchmark list, including catch-all domains.
The free tier doesn't trade accuracy for the price tag. It caps volume only. Every check the paid Email Verification API runs to judge deliverability is the same check the tester on this page runs.
Can I test a whole list for deliverability in bulk for free?
Yes. The free tier gives you 1,000 tests (2,500 if you sign up with a work email), so you can run a deliverability check across most small lists outright before a send.
For larger lists, our paid credit packs are pay-as-you-go and never expire, with pricing localized to your region on the pricing page. CSV upload, API access, and bulk parallel processing are included from the free tier up. If you prefer the validator phrasing, the free email validator runs the identical engine on bulk lists.
What is a good email deliverability rate?
On the address level, you want effectively all the mailboxes on your list to be live before you send. Mailbox providers start throttling and spam-foldering once hard bounces cross roughly 2 %, so the practical target is to get your undeliverable count to under 1 % by removing dead addresses ahead of the send.
Testing deliverability up front is the cheapest way to protect the sender reputation that every later send depends on. Pair it with a blacklist check to cover the domain-reputation side of the deliverability picture too.
Do you store the emails I test?
No. Addresses are processed in memory and discarded the moment the deliverability test completes. Nothing logged, nothing retained, nothing sold.
We're SOC 2 Type II compliant with the full Trust Center report on request. Read the privacy policy for the byte-by-byte breakdown of what we touch and what we don't.
What happens when I hit the daily limit?
Either wait 24 hours, or create a free account to claim 1,000 tests instantly (2,500 if your signup email is a work address). No card required for the signup tier either.
Most teams move to a paid credit packonce they're testing deliverability across lists of 10,000+ addresses before every campaign.
How fast is the API and what's the SLA?
Median latency is around 380 ms for a single address, sub-50 ms for cached results. Bulk deliverability testing runs at roughly 10,000 emails per minute on the standard tier.
SLA is 99.9 % uptime on Starter, 99.99 % with an annual Volume contract. Full real-time uptime + incident history at status.verifox.ai. Implementation details in the API docs.
Can I add deliverability testing to my own app or AI agent?
Yes. The REST API reference documents the inbound and outbound shapes for every endpoint, so you can drop real-time deliverability testing into signup forms, CRMs, or any tool that speaks REST. HubSpot, Salesforce, Zapier, Klaviyo, Mailchimp, and Brevo all connect out of the box.
Verifox also ships native MCP server support so AI agents (Claude, Cursor, custom LLM apps) can test deliverability without glue code. Drop the MCP URL into your agent config and the tools are wired.