001INPUT
Paste the address
Drop any email into the pill. Gmail, Outlook, custom domains, role aliases. Single address now, bulk CSV on signup.
Email Testing, One Engine
Email Testing Platforms Preview the Message. This One Tests the Mailbox.
Run the MX lookup, the SMTP handshake, and the SPF, DKIM, and DMARC checks a real receiving server runs, on the same 9-point engine our paid API uses. 99.99% accuracy, no signup, no card.
Trusted by 500,000+ leading GTM teams of all sizes
From paste to verdict
How the email testing engine works
Three steps, no signup, no card on file. Paste any address, watch nine checks fire in parallel, and read an accept-or-bounce 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.
Eight tools, one engine
Eight email testing tools, all on one account
Every tool below queries the same engine and the same live DNS and SMTP data, so a verdict on one page means the same thing on every other. Start with the check your send needs today; the rest share your free credits.
Free Email Checker
Paste one address, get the full 9-point verdict in about two seconds.
Open the toolEmail Deliverability Tester
Confirms a mailbox is live and will accept mail before you send to it.
Open the toolSMTP Test
Runs the handshake a receiving server runs, without delivering anything.
Open the toolDKIM Tester
Reads your DKIM record and flags broken or misaligned signing keys.
Open the toolSPF, DKIM + DMARC Check
The full authentication stack in one pass, explained in plain English.
Open the toolMX Lookup
Resolves a domain's mail routes and spots missing or misordered records.
Open the toolEmail Blacklist Check
Screens sender reputation so a listed domain never surprises you mid-send.
Open the toolMultiple Email Checker
Tests a batch of addresses at once; bulk CSV runs at 10,000 per minute.
Open the toolHow 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 platform
One email testing platform, not five subscriptions
Most platforms in this category charge per seat for previews and leave the acceptance layer to someone else. Verifox runs the full nine-check pipeline the paid plans use on every free test, 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.
Choosing an email testing platform
What email testing platforms do, and where most of them stop
Search for email testing platformsand you will find two product families wearing the same name. The first tests the message: rendering previews across forty clients, broken-link scans, spam-word scoring, seed-list sends that report which folder you landed in. The second tests the plumbing underneath the message: whether your domain's authentication records hold up, whether the receiving server will open a connection at all, and whether the addresses you are about to mail actually exist. Most teams buy the first family, skip the second, and then watch a beautiful template bounce off a meaningful slice of their list.
Verifox sits squarely in the second family, the layer where deliverability is won or lost. Each test runs the conversation a real receiving server would: an MX lookup to find the mail route, an SMTP handshake to confirm the mailbox is live, and a read of your SPF, DKIM, and DMARC records on the sending side. All of it feeds the same 9-point engine behind our email verification service, which scored 99.99% accuracy on a 1,000-address benchmark, including the catch-all domains where 20 to 40% of B2B lists quietly fail and where most free tools simply give up.
The practical workflow is short. Test the list first, because dead mailboxes poison every later signal: the deliverability tester tells you which addresses will accept mail before anything goes out. Then check authentication before each campaign, since a single rotated DKIM key can undo months of sender reputation. You can run all of it on the free tier, 4 checks a day without an account and 1,000 free credits on signup, and credits that never expire when your volume grows past it. No platform fee stands between you and the first test.
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 testing platforms, answered
What teams comparing email testing platforms ask us before they commit, with the real numbers, the real limits, and a few honest opinions about what testing can and cannot prove.
What is an email testing platform?
An email testing platform checks a message and the infrastructure behind it before a real send, so problems show up in a dashboard instead of a bounce report. The category covers rendering previews, spam-content scoring, authentication checks (SPF, DKIM, DMARC), SMTP and MX diagnostics, and recipient-address verification.
Verifox covers the infrastructure and recipient side: it proves whether mail will be accepted at all, using the same 9-point verification engine across every tool on the platform.
What is the difference between email testing and email verification?
Email testing examines your side of the send: templates, links, authentication records, reputation. Email verification examines the recipient side: whether each address on your list exists and will accept mail.
The two fail independently. A perfectly authenticated domain still bounces off dead mailboxes, and a clean list still lands in spam if DKIM is broken. Verifox puts both layers on one account: the free email checker for addresses, the DKIM tester and its siblings for your sending setup.
Which checks should an email testing platform run?
At minimum, the nine that decide whether a message gets accepted:
- 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 detection + AI-confidence scoring
- Domain age
- SPF, DKIM, and DMARC authentication
Verifox runs all nine in parallel on every test. The full breakdown lives on the email verification service page.
Do I need a paid platform to test SPF, DKIM, and DMARC?
No. Authentication records are public DNS data, and reading them should not cost anything. Verifox ships a free DKIM tester and a combined SPF, DKIM, and DMARC checker that read your records and flag misalignment in plain English.
Where paid platforms earn their keep is volume: testing thousands of addresses before a campaign, or wiring checks into a signup form via the API. The record-reading stays free.
Can an email testing platform tell me if I will land in spam?
Only partly, and any platform claiming certainty is overselling. Inbox placement depends on your content, your sending history, and each provider's filters. What a platform can prove is the acceptance layer: valid authentication, a live mailbox, a clean sending domain.
Get those right and placement problems become content problems you can iterate on. Start with the spam check for address risk and the blacklist check for sender reputation.
How much does an email testing platform cost?
Verifox is free to start. You get 4 checks per day on this page without an account, then 1,000 free credits on signup, or 2,500 if you sign up with a work address. No card required.
Past that, credits are pay-as-you-go and never expire, with volume pricing shown for your region on the pricing page. No seat fees, no lock-in.
Can I test a whole email list before a campaign?
Yes, and you should: mailbox providers throttle senders once hard bounces climb, so testing the list is the cheapest insurance a campaign can buy. Bulk runs process roughly 10,000 emails per minute on the standard tier, with CSV upload included from the free tier up.
Paste a handful into the multiple email checker to try it, then upload the full file once you have claimed your free credits.
Do you store the emails I run through the platform?
No. Every address is processed in memory and discarded the moment the test completes. Nothing logged, nothing retained, nothing sold.
Verifox is SOC 2 Type II compliant with the full Trust Center report available on request. The privacy policy spells out exactly what we touch and what we never see.
Can I wire email testing into my own app or AI agent?
Yes. The REST API returns a verdict in around 380 ms median, sub-50 ms cached, so real-time testing inside signup forms and CRMs is practical. HubSpot, Salesforce, Zapier, and Klaviyo connect out of the box.
For AI agents, Verifox ships a native MCP server: drop the URL into a Claude or Cursor config and the testing tools are wired without glue code. Uptime history is public at status.verifox.ai.
How accurate is Verifox compared with other email testing platforms?
99.99% accuracy on a 1,000-address benchmark list, self-measured, including catch-all domains. Catch-alls are the honest differentiator: 20 to 40% of B2B lists sit behind domains that accept everything during a basic SMTP probe, and most platforms skip them or mark them unknown.
Verifox runs an AI-confidence pass on every catch-all instead of giving up. The free tier runs the identical engine the paid verification API runs, capped only on volume.
Start testing
Test your next send before your prospects see it.
Signup takes under a minute and starts you with 1,000 free credits, or 2,500 if you use a work address. Every credit runs the full 9-point test, they never expire, and there is no card and no subscription to cancel later.
No card required. Volume pricing is shown for your region.