Syntax & MX check
Confirms the address is well-formed and that the domain has a working mail server.
Runs before a credit is spent, so malformed rows and dead domains never cost you anything.
Accurate · Fast · Secure
Verify Every Email. Reach Real People.
SF Email Verifier removes invalid, risky, and catch-all emails, and resolves the Gmail and Yahoo addresses others give up on, so you boost deliverability and reduce bounces.
99%+
Accuracy
20/day
Free forever
Gmail+
Yahoo deep
API
+ bulk CSV
Verification resultsThis month
95.3%Deliverable
- Deliverable0
- Risky0
- Undeliverable0
- Unknown0
Total verified
0
↑ 24.5%
Bounce rate
0.3%
↓ 87%
Avg. time
2.4s
↓ 65%
Verify an email
Trusted by 1000+ businesses
4.8/5
“Incredible accuracy and speed.”
4.9/5
“The best email verification tool we've used.”
4.7/5
“Improved our deliverability dramatically.”
/// how verification works
Four checks, one credit, an answer you can trust.
Every address walks the same four stages. You are charged once, and only when we can give you a definitive answer.
- Unknown results are never charged
- Bulk files up to 50,000 rows
- Same engine on the API and the dashboard
SMTP handshake
Connects to the real mail server and asks whether that specific mailbox accepts mail.
This is the step most checkers stop at, and where a generic tool starts guessing.
Provider-specific resolution
For Gmail and Yahoo, runs deeper checks instead of defaulting to a catch-all label.
Available on single verification. In bulk these addresses are skipped and cost no credit.
Disposable & role detection
Flags throwaway domains and generic addresses like info@ or support@.
You decide how to treat them rather than us silently dropping them from your list.
Why most verifiers fail
Gmail and Yahoo break standard email checkers.
Yahoo's mail servers use enumeration protection, and Gmail Workspace domains behave similarly. A plain SMTP check can't tell a real inbox from a fake one on those domains, so most tools either rubber-stamp every address as valid, or give up and flag the entire domain catch-all.
Other tools
Mark the entire Yahoo domain “catch-all”, meaning even your most valuable, real contacts get skipped and ignored.
SF Email Verifier
Runs deeper, provider-specific checks so real Gmail and Yahoo mailboxes come back valid, and fakes come back definitively invalid.
/// why choose us
Built to be accurate where it's hard.
The numbers that matter when you're protecting your sender reputation.
99.2%
Verdict accuracy
On a public 50k labeled set, on par with ZeroBounce and NeverBounce, ahead on Gmail/Yahoo.
Gmail + Yahoo
Provider-deep checks
Resolve the catch-all ambiguity that makes most tools rubber-stamp or skip real mailboxes.
0 charged
Pay only for answers
Unknown and greylisted results never cost a credit, ambiguity is on us, not you.
~800ms
Fast, then thorough
Single checks in under a second; bulk lists stream in the background at scale.
Single email verifier
Check one address in real time: syntax, MX records, SMTP handshake, disposable and role-based detection.
Try a live checkBulk email verifier
Upload a CSV and clean thousands of addresses in the background. Unknown results are always free.
Clean a listEmail finder by name
Enter a full name and a company domain to surface and verify the most likely real address.
Find an addressReverse email lookup
Already have an address? Find the name and company behind it before you reach out.
Look one upVerification API
Call the same engine that powers the dashboard directly from your signup form or outreach tool.
Read the docsGmail & Yahoo accuracy
Provider-specific checks resolve catch-all ambiguity instead of giving up on it. Deepest on single verification.
See how/// features
Verify what you have. Find what you don't.
One engine, one credit wallet. Everything below runs on the same verification core, whether you click it or call it from your own code.
See what a credit buys/// speed
Fast where it counts. Thorough where it matters.
Major providers resolve without a live mailbox probe, so those addresses move quickly. Everything else gets a real SMTP conversation, deliberately paced so mail servers keep answering us honestly.
Major providers and repeat domains
Gmail, Yahoo, Outlook and any domain we have already resolved. Answered from syntax, MX and our provider data, no probe needed.
Throughput
100K+ per hour
Per address
Well under a second
Domains that need a live probe
Company and catch-all-protected domains get a real SMTP check, capped at 30 concurrent probes so we stay welcome on the receiving end.
Throughput
10K to 30K per hour
Per address
12s hard timeout
Real throughput depends on your domain mix, and large jobs are queued rather than run all at once. Files up to 1,000,000 rows are supported, progress streams live, and unknown results are never charged.
/// built for
One engine, every outreach workflow.
Marketers
Clean your list before every send so bounces stay low and your domain keeps landing in the inbox.
- Bulk CSV cleaning
- Lower bounce rate
- Protect sender reputation
Developers
Validate addresses at signup with a single API call. JSON in, a clear status out, no guesswork.
- REST API on every plan
- Verify at signup
- Webhooks on completion
Agencies & sales
Find the right address by name and domain, verify it, then reach out with confidence.
- Email finder + reverse lookup
- Per-client lists
- Predictable credit pricing
Zapier
HubSpot
Mailchimp
Salesforce
Klaviyo
Slack
Clay
Sendgrid
/// integrations
Verification for all your favorite platforms.
Connect the verification API to the marketing, CRM, and outreach tools you already use, verify a list in bulk or clean addresses in real time as visitors submit them.
REST API, signed webhooks, and CSV import work with website builders, CRMs, and email platforms, Zapier, HubSpot, Salesforce, Mailchimp, Klaviyo and more.
/// security & privacy
Your lists are yours. Full stop.
We never sell, share, or train on the data you upload.
Encrypted at rest
Uploaded lists are encrypted on disk and in transit over TLS.
GDPR + CCPA
Built to comply with EU and California data-protection rules.
Auto-deleted in 7 days
Bulk jobs and their files are purged automatically after a week.
No data resale
We never sell, share, or train models on your contacts.
/// compare
See how we stack up before you commit.
Honest, feature-level comparisons, including where the other tool is genuinely a better fit.
/// what people say
Teams who care about deliverability.
“We cut our bounce rate from 9% to under 1% in a week. The Gmail and Yahoo results are the ones I actually trust now.”
“Dropped the API into our signup form in an afternoon. Fake addresses just stopped getting through.”
“Unknown results being free is the honest touch. We only pay for answers we can act on, so the pricing finally makes sense.”
“I uploaded a 40,000 row list on a Friday afternoon and had the cleaned file back before I left. No babysitting the tab.”
“The catch-all handling is what sold me. Other tools shrug and mark the whole domain risky. This one actually gives me an answer per address.”
“Our sender reputation was in the gutter after an old list went out. Two cleanups later, inbox placement is back where it should be.”
“Docs were clear enough that I never opened a support ticket. Auth, batch endpoint, webhooks, all working on the first try.”
“We were paying roughly three times this for results that were no better. Switching was the easiest budget win of the quarter.”
“Free tier let me test it against a list I already knew the answers to. It matched, so I upgraded the same day.”
/// questions
Quick answers
Is it really free?
Yes, 20 verification credits every day, forever. No card, no trial clock. Unknown results never cost a credit.
How accurate is it on Gmail and Yahoo?
We run provider-specific checks for Gmail/Workspace and Yahoo Mail instead of defaulting to a generic catch-all label, so real mailboxes come back valid and fakes come back invalid.
Can I verify a whole list at once?
Upload a CSV (up to 1M rows). Jobs run in the background and download as a clean list. Files auto-delete after 7 days.
Is there an API?
Yes, on every plan, including the free tier. Call the same engine from your signup form, CRM, or outreach tool.
What does “catch-all” mean in email verification?
A catch-all domain accepts mail at any address, even ones that don’t exist, so a standard SMTP check can’t tell a real inbox from a fake one. Most verifiers respond by flagging every address on that domain as catch-all and refusing to guess. We run deeper, provider-specific checks on Gmail and Yahoo instead of stopping there.
What’s the difference between invalid, risky, and unknown results?
Invalid means the mailbox doesn’t exist or the domain has no working mail server. Risky covers disposable, role-based (info@, support@), or catch-all addresses that need a judgment call. Unknown means the mail server wouldn’t give a definitive answer.
Which results cost a credit?
Only definitive ones. Unknown and greylisted results are always free, so a mail server that refuses to answer never costs you anything. Valid, invalid, catch-all, role and disposable results each cost one credit, because each is an answer you can act on.
How does SF Email Verifier compare to ZeroBounce or NeverBounce?
On ordinary business domains the three are close. The difference shows on Gmail and Yahoo addresses, where those tools tend to fall back to a catch-all label and we run provider-specific checks to reach a real verdict.
Do you send an email to verify it?
No. We open a one-line SMTP handshake to ask the mail server whether the mailbox accepts mail, but no message is ever sent. The mailbox owner never sees anything land in their inbox.
Start verifying for free, right now.
20 credits every day, forever. No credit card, no trial clock.