A complete engineering toolbox for real-time SMTP email verification, DNS authentication (MX, SPF, DKIM, DMARC, PTR, BIMI), B2B lead discovery, and spam filter diagnostics.
Test your sending domain (SPF, DMARC, 6 DNSBLs) + 220 subject/body spam triggers for an instant 0–100 Spam Score.
Is my email blacklisted? Check Spamhaus ZEN, SpamCop, Barracuda & SORBS in real time.
Paste up to 10 First Name, Last Name & Company Domain rows to permute and verify work emails via live SMTP.
Test whether a single email or CSV/.XLSX list will return a 550 Hard Bounce without sending an email.
Are email addresses case sensitive? Normalize mixed-case lists to lowercase and strip case-collision duplicates.
Inspect local-part and domain syntax rules (dashes, dots, plus tags, length) and B2B corporate email formats.
Detect Gmail dot aliases, +tag subaddresses, Apple Hide My Email, SimpleLogin, and department role aliases.
Run a consultant-grade 360° deliverability diagnostic and benchmark the top 15 deliverability tools of 2026.
Predict Primary Inbox vs Promotions vs Spam placement on Gmail, Microsoft 365 & Yahoo by testing live DNS + copy.
Test whether any domain or B2B address is a Catch-All (Accept-All) server via randomized SMTP control probe.
Inspect up to 10 domains simultaneously for MX servers, SPF, DMARC policy, and DNSBL blacklists.
Modern browser alternative to Email Extractor 1.6 / 1.4 / Lite — extract & send directly to Bulk SMTP Cleaner.
1-click audit of MX, SPF, DKIM, DMARC & 6 DNSBL blacklists with an A+ to F grade and embeddable security badge.
Verify a single email address in real time — syntax, MX, SMTP probe, catch-all and typo suggestion.
Find and verify anyone's work email address from their First Name, Last Name and Company Domain via live SMTP.
Extract, deduplicate, and filter email addresses from raw text, HTML source, PDFs, or CSV logs 100% in your browser.
Build a v=spf1 TXT record for Google Workspace, M365, SES & SendGrid with a live RFC 7208 10-lookup counter.
Create a Gmail & Yahoo 2026 compliant _dmarc TXT policy (none, quarantine, reject) with RUA reporting.
Inspect any _domainkey TXT record, auto-scan 14 common selectors, and verify 2048-bit RSA public key strength.
Generate a 1024-bit or 2048-bit RSA DKIM private key and DNS _domainkey TXT record locally in your browser.
Check PTR records and Forward-Confirmed Reverse DNS (FCrDNS) for any sending IP or domain MX servers.
Verify your default._bimi TXT record, SVG Tiny PS logo, VMC certificate, and DMARC enforcement readiness.
Inspect your domain's v=spf1 record, count DNS lookups against the 10-lookup limit, and validate -all / ~all.
Validate _dmarc TXT policy (none, quarantine, reject), subdomain policy, and RUA/RUF reporting.
Check a domain's mail servers (MX records + priority), fingerprint the provider, and grade MX redundancy.
Scan your subject line and email body for 180+ spam trigger phrases, ALL CAPS, and phishing patterns.
Detect temporary, throwaway and burner email addresses (10MinuteMail, YOPmail, Mailinator) before they enter your CRM.
Quickly check whether an email address looks valid and deliverable, free and without signup.
Estimate how much you save by cleaning your list vs ZeroBounce, NeverBounce, Bouncer and Kickbox.
Verify @gmail.com, @googlemail.com & Google Workspace custom domains with dot/plus alias normalization.
Verify @yahoo.com, @ymail.com & @rocketmail.com accounts and filter out 12-month dormant spam traps.
Verify @outlook.com, @hotmail.com, @live.com & Microsoft 365 Exchange Online Protection tenants.
Verify @icloud.com, @me.com, @mac.com and detect Apple Hide My Email private relay addresses.
Verify encrypted @proton.me, @protonmail.com, @pm.me & custom Proton Business domains via Swiss MX.
Verify legacy @aol.com, @aim.com & migrated @verizon.net addresses to prevent Yahoo/AOL blocks.
Reliable inbox placement across Gmail, Microsoft 365 (Outlook/Hotmail), Yahoo, and Apple iCloud requires coordinating four technical layers: DNS & Cryptographic Authentication, IP/Domain Reputation, Pre-Send SMTP List Hygiene, and Content & Header Compliance. Use the matrix below to run a complete diagnostic across your sending infrastructure in under 3 minutes:
| Diagnostic Layer | Recommended Free Tool | RFC / Provider Standard | Pass Threshold for 2026 Bulk Senders |
|---|---|---|---|
| 1. Mail Routing & Reverse DNS | MX Lookup & PTR Lookup | RFC 5321 / RFC 1912 FCrDNS | 2+ redundant MX hosts; matching forward/reverse PTR records on all outbound IPs. |
| 2. Sender Policy Framework (SPF) | SPF Checker & SPF Generator | RFC 7208 Section 4.6.4 | Single v=spf1 TXT record, ≤10 recursive DNS lookups, ending in ~all or -all. |
| 3. DKIM & DMARC Enforcement | DKIM Checker & DMARC Checker | RFC 6376 / RFC 7489 | 2048-bit RSA DKIM selector + aligned _dmarc policy (p=quarantine or p=reject) with rua=. |
| 4. Blacklists & Spam Triggers | Blacklist Checker & Spam Checker | Spamhaus ZEN / Gmail Postmaster v2 | 0 listings across 6 major DNSBLs; Spam Score < 15/100; user complaint rate < 0.1%. |
| 5. Pre-Send SMTP List Hygiene | Email Validator & Catch-All Verifier | 7-Layer Smart SMTP Handshake | Hard bounce rate strictly < 0.5%; all invalid, disposable & deactivated mailboxes removed pre-send. |
Yes. Every interactive diagnostic tool in the KaijuVerifier toolbox—including our real-time SMTP email validator (20 checks/min free), SPF/DKIM/DMARC checkers and generators, DNSBL blacklist scanner, PTR lookup, and in-browser bulk email extractor—is 100% free with no account or credit card required.
Run a 3-step diagnostic: first, audit your sending domain with the 360° Email Deliverability Test and Blacklist Checker to verify MX, SPF (≤10 DNS lookups), DKIM (2048-bit RSA), and DMARC (p=quarantine or p=reject). Second, scan your campaign copy with the Email Spam Checker. Third, scrub your subscriber CSV/XLSX in the Bulk Email Cleaner to eliminate 550 hard bounces and disposable traps.
Our 7-Layer Smart SMTP engine validates RFC 5322 syntax, resolves the recipient domain's MX servers, performs a non-intrusive EHLO / MAIL FROM / RCPT TO handshake without transmitting a message body (DATA), probes for Catch-All behavior using a randomized control address, and checks 1M+ disposable domains.
Yes. KaijuVerifier provides a developer-first REST API (/api/v1/verify-single and /api/v1/verify-batch) with HMAC-SHA256 signed webhooks, plus 100 free monthly API verifications and $0 charged for Unknown or duplicate rows.
Need to clean a whole list? Upload a CSV or Multi-Sheet Excel (.xlsx) file to the Bulk Email Cleaner or integrate real-time checks with our Email Verification API.