Free email & DNS tools
A complete toolkit for email deliverability, authentication and DNS — verification, SPF/DKIM/DMARC, blacklists, SMTP, BIMI and more. No sign-up needed for basic results.
Outbound Deliverability Test
Send a real email to a unique address — we grade your actual sending identity, auth & content.
Open the tool →DMARC Monitor
See who’s sending as your domain. We ingest your DMARC aggregate reports and turn them into readable dashboards — SPF/DKIM alignment, sending sources, and a safe path to p=reject.
★ Most useful
7One report scoring your domain’s routing, auth, TLS and reputation.
Paste raw headers to trace the path and authentication results.
Connect to a mail server and check banner, STARTTLS and TLS.
Check an IP or domain against reputation blocklists.
Verify a single address: syntax, MX, mailbox, disposable and more.
Inspect a DMARC record, its policy strength and reporting setup.
Gmail / Yahoo / Outlook readiness for high-volume senders (2024+ rules).
✓ Email verification
8Detect throwaway / temporary-mail domains.
Detect accept-all domains where acceptance proves nothing.
Check email syntax and get a suggested correction.
“Did you mean gmail.com?” — catch fat-fingered domains.
Flag shared role mailboxes (info@, support@, sales@).
Paste a list to spot duplicates, syntax errors, role and free-provider addresses, and domain concentration — before you verify.
Check a CSV for delimiter, encoding, the email column and malformed rows before uploading it for verification.
Estimate the wasted sends and cost of mailing an unverified list — and what cleaning it saves.
⚙ DNS & authentication
11Find a domain’s mail servers, priorities and resolved IPs.
Validate an SPF record and count its DNS lookups against the limit of 10.
Look up a DKIM key by selector and check its type, length and status.
Build a safe DMARC record with a staged rollout.
Generate a valid SPF record from your sending providers.
Build a BIMI record for your logo, with the DMARC/VMC prerequisites.
Can someone forge mail from your domain? Weighs SPF, DKIM and DMARC.
Expand your SPF record into a tree and count DNS lookups visually.
Check whether a zone is DNSSEC-signed and properly delegated (DS).
Generate an RSA DKIM keypair in your browser + the DNS record.
Check a logo against the SVG Tiny P/S profile BIMI requires.
🛡 Deliverability & security
6Check PTR and forward-confirmed reverse DNS for a mail IP.
Check the MTA-STS policy that requires TLS for inbound mail.
Verify TLS reporting so you hear about failed TLS deliveries.
Check the BIMI record that shows your logo in the inbox.
Check List-Unsubscribe & one-click headers for Gmail/Yahoo bulk rules.
Check TLSA records for SMTP and whether they’re DNSSEC-validated.
🩺 Diagnostics
4Compare a DNS record across multiple public resolvers after a change.
Decode an SMTP reply or bounce code (250/421/550, 5.1.1…) and what to do.
Paste a bounce / DSN to decode its SMTP and enhanced status codes into a plain-English cause and fix.
Paste a payload, secret and signature to verify your HMAC-SHA256 webhook validation — all in your browser.