Clean your lists, stop bounces, and protect your sender reputation with 98.5%+ accuracy. Test any email or batch live below, or unlock 5,000 never-expiring credits for $19.
Stop guessing. Our multi-stage verification engine checks syntax, DNS/MX records, disposable databases, and live SMTP handshakes to protect your sender reputation.
Your privacy is built into our architecture. Files are processed strictly in volatile RAM and purged immediately after verification. We never store or resell your lists.
CRMs and ESPs charge by subscriber count. Remove invalid, disposable, and role-based addresses before importing so you only pay for real, reachable contacts.
Explore our verification tools & guides
Clean any CSV or Multi-Sheet Excel workbook in under 60 seconds with zero setup.
Drag and drop your `.csv`, `.xls`, or multi-sheet `.xlsx` file. Our engine automatically finds the email column across your sheets.
We validate syntax, DNS/MX records, 1M+ disposable domains, role accounts, catch-all servers, and live SMTP mailbox responses in parallel.
Export your deliverable leads, invalid report, or your original multi-sheet Excel workbook with only bad emails removed.
Our multi-layer verification engine goes far beyond basic syntax checks with real-time SMTP handshakes and intelligent domain filtering.
First line of defense. We verify email format follows strict RFC 5322 standards, checking structure, invalid characters, and domain typos.
We query live DNS records to confirm the domain exists and has active Mail Exchange (MX) servers configured to receive messages.
Real-time SMTP protocol verification (`EHLO` / `RCPT TO`) connects directly to the mail server without sending an actual email.
Verifies that the specific recipient mailbox is active and able to receive mail, flagging disabled accounts and full inboxes.
Continuously updated database of 1M+ disposable & burner domains (Temp-Mail, Guerrilla Mail, 10MinuteMail, Mailinator).
Curated blocklist of toxic and abusive domains known for spam complaints, honeytraps, and bot activity.
Detects 110+ high-risk patterns including spam keywords, keyboard-mash strings, and automated bot signups.
Flags shared group inboxes (`info@`, `support@`, `sales@`, `admin@`) that lower cold-outreach engagement and GDPR compliance.
Eliminate permanent delivery failures caused by non-existent mailboxes, dead domains, and deactivated employee accounts.
Detect temporary issues like full mailboxes, rate-limited servers, or transient MX errors before launching your campaign.
Identify corporate mail servers configured as `accept-all` so you can segment high-confidence leads from catch-all domains.
Smart detection of mail servers using greylisting anti-spam defenses, preventing false negatives on valid corporate emails.
Everything enterprise senders expect from ZeroBounce or NeverBounce — at up to 80% lower cost and with native multi-sheet Excel support.
Other verifiers force you to flatten workbooks into single-sheet CSVs. Upload a multi-tab .xlsx workbook and download it back with every sheet, column, and tab name intact.
Your customer lists are processed strictly in volatile RAM and purged immediately upon completion. We never store, resell, or log your raw email contacts on disk.
Beyond static blacklists, our engine fingerprints MX server clusters in real time to catch brand-new burner domains, catch-all servers, greylisting, and role accounts.
Yes — the free plan includes 100 verifications per month with no credit card required. One-time credit packs start at $19 for 5,000 credits (never expire), and monthly plans start at $19/mo for 10,000 verifications.
We use a comprehensive 7-layer verification pipeline including RFC syntax validation, DNS/MX record verification, real-time SMTP handshakes, and mailbox checks. Combined with our 1M+ disposable domain database and toxic domain filtering, we achieve 98.5%+ accuracy.
Absolutely not. We enforce a strict Zero-Retention Policy. Your files are processed in volatile RAM and deleted immediately after you download your results. We never log, store, or resell your contact data.
We support .CSV, .XLS, and .XLSX files. Our parser automatically detects the email column regardless of how it is labeled, and preserves all sheets in multi-tab Excel workbooks.
Beyond basic syntax and MX checks, we include a 1M+ disposable email database, toxic domain blocking, spam pattern detection, role-based account flagging, catch-all identification, greylisting-aware retries, and multi-sheet Excel preservation.
Some corporate mail servers block external verification attempts or return ambiguous responses. Rather than guessing, we mark them as "Unknown" and never charge credits for Unknown or Duplicate rows ($0).
Disposable emails are temporary burner addresses (Temp-Mail, Guerrilla Mail, 10MinuteMail) that expire in minutes and have zero commercial value. Our database tracks over 1 million disposable domains to keep fake signups out of your CRM.
Upload an Excel workbook with multiple tabs (e.g., `Contacts`, `Sales`, `Accounts`) and our Cleaned Database export preserves every tab with its original name and formatting while removing invalid emails from the contact sheet.
Hard bounces are permanent delivery failures (non-existent mailbox, dead domain) that must be removed immediately. Soft bounces are temporary issues (full inbox, server busy). We clearly separate both in your report.
Yes. Cleaned CSV and Excel files import directly into HubSpot, Mailchimp, Klaviyo, SendGrid, ActiveCampaign, Instantly, Smartlead, and any other ESP or outreach platform.
Our parallel engine verifies typical lists in seconds to a few minutes. Larger lists (50k+ rows) are processed asynchronously with live progress updates so you can download your cleaned file as soon as it finishes.
Yes. Because all verification runs in volatile memory with zero disk retention and TLS 1.3 encryption in transit, KaijuVerifier is designed from the ground up for EU/GDPR data minimization and privacy compliance.
Modern email deliverability requires more than regex syntax checks. Google Postmaster Tools, Yahoo Sender Hub, and Microsoft SmartScreen enforce a strict 0.3% spam complaint threshold and penalize senders whose hard bounce rate exceeds 1.5%. KaijuVerifier executes a deterministic 7-Layer Smart SMTP & DNS pipeline in under 380ms — combining RFC 5322 grammar validation, IDN punycode decoding, Levenshtein consumer typo correction (gmial.com → gmail.com), a 112,000+ disposable domain graph, canonical Gmail +alias normalization, catch-all canary entropy probing, and a non-intrusive TLS 1.3 RCPT TO handshake.
Whether you are scrubbing a multi-sheet Excel (.XLSX) workbook exported from HubSpot or Salesforce, or validating user registrations in real time via our REST API (/api/v1/verify-single), KaijuVerifier guarantees 99.7% precision on definitive outcomes and charges $0 for inconclusive greylisted unknowns. When reaching out to our engineering desk, you can include your sending domain, sample SMTP 550/421 diagnostic logs, or your expected monthly API verification volume so a senior postmaster specialist can run a live DNS, MX, SPF, DKIM, DMARC, and PTR pre-assessment before replying. Enterprise procurement teams can also request SOC 2 / ISO 27001 security documentation, custom rate-limit allocations above 250 requests per second, and dedicated isolated worker pools. Each connector in our integration library supports both synchronous point-of-capture validation (blocking invalid syntax, Levenshtein ISP typos, and 112,000+ disposable burner domains in under 180 milliseconds) and scheduled asynchronous batch scrubbing for existing contact tables. By mapping KaijuVerifier’s composite 0–100 score and granular boolean flags directly into custom CRM properties, your marketing automation workflows can segment verified deliverable leads from catch-all domains automatically. Our engineering culture emphasizes deep protocol mastery, zero-bloat architecture, and measurable customer impact. Every member of the KaijuVerifier team works directly on core challenges such as adaptive anti-greylisting state machines, real-time disposable domain graph indexing, multi-tab Excel workbook streaming, and low-latency edge APIs that process millions of B2B and consumer verifications daily without data retention. In addition to real-time TCP port 25 and TLS 1.3 handshake monitoring, our telemetry daemon continuously executes synthetic canary verifications against Gmail, Google Workspace, Microsoft 365 Exchange Online Protection, Yahoo/Ymail/AOL, Apple iCloud, and ProtonMail every 60 seconds. If any autonomous system number (ASN) experiences elevated latency or transient 421 rate deferrals, traffic shifts seamlessly to healthy regional clusters. Following this Mailchimp hygiene workflow before every major seasonal broadcast or newsletter send ensures your Intuit Mailchimp account never triggers an Omnivore compliance lock. Furthermore, because Mailchimp bills monthly based on total stored contacts across all audiences, permanently deleting verified 550 hard bounces and disposable burner addresses immediately lowers your monthly recurring ESP overhead. Each chapter of the playbook includes copy-paste DNS zone templates, Postfix and Amazon SES header configurations, DMARC XML aggregate report parsers, and SQL/CSV segmentation queries tested across hundreds of millions of production B2B and e-commerce emails. Engineering and RevOps teams use this playbook as their standard operating procedure during domain warm-up and CRM migrations. Auditing your sending domains against this checklist before scaling outbound or lifecycle volume protects your organization from both technical blocklisting (Spamhaus ZEN, Barracuda, Microsoft SNDS) and regulatory GDPR privacy inquiries. Keep a dated copy of your SPF, DKIM, DMARC, BIMI, PTR, and batch list-cleaning logs as part of your internal compliance documentation. Because the Chrome Extension communicates directly with our global TLS 1.3 edge API and executes DOM email extraction locally inside your browser sandbox, no browsing history or third-party webpage content is ever transmitted to external servers. SDRs and recruiters can verify individual executive mailboxes on the fly or batch-clean extracted prospect lists in seconds.
| Verification Layer | Protocol / RFC Standard | Latency & Precision Benchmark |
|---|---|---|
| Layer 1–2: Syntax, Punycode & Typo Guard | RFC 5322 / RFC 5891 IDNA + Levenshtein Distance | < 2 ms · Catches @gmial.com, @yaho.com, @hotmial.com at $0 |
| Layer 3–4: Disposable & Role Classifier | 112,000+ DEA Domain Graph + Role Prefix Lexicon | < 10 ms · Blocks Yopmail, Temp-Mail, Guerrilla Mail & Gmail +aliases |
| Layer 5: Authoritative DNS & MX Inspection | RFC 1035 MX Priority + SPF/DMARC/DNSBL Telemetry | 45 ms · Fingerprints Google Workspace, Microsoft 365, Yahoo/Ymail & Proofpoint |
| Layer 6–7: Catch-All Canary & Smart SMTP | RFC 5321 EHLO / MAIL FROM / RCPT TO over TLS 1.3 | 180 ms · 99.7% Mailbox Accuracy with $0 Charge on Unknowns |