Maxinames

Free tool

Email Deliverability Check

Diagnose SPF, DKIM, DMARC, MTA-STS, DANE, BIMI, and blocklist issues for any domain. Results in seconds. No account, no test email to send — everything runs in your browser.

Find your selector in any received email under DKIM-Signature: s=.

Lookups run in your browser via Cloudflare DNS-over-HTTPS plus one HTTPS fetch for the MTA-STS policy. Domains are not stored.

What we check

Ten focused checks across delivery, authentication, transport, and reputation — the things that actually decide whether your mail lands in the inbox.

Delivery

MX records, A records on each MX host, and reverse DNS — the basics that block incoming and outgoing mail when broken.

Authentication

SPF (with lookup-count budget), DKIM (selector probe), and DMARC (with policy strength and reporting checks).

Transport security

MTA-STS policy fetch, TLS-RPT reporting, and DANE/TLSA per MX host. Stops downgrade attacks against SMTP TLS.

Reputation

Live blocklist queries against Spamhaus, SpamCop, Barracuda, and PSBL for every MX IP. Flag listings before receivers reject your mail.

Need a deeper test that includes the live SMTP banner, port 25 reachability, or a "send a real email and grade it" flow? Those need server-side testing — open a support ticket and we will run a deeper audit for you.

All DNS lookups go through Cloudflare's public DNS-over-HTTPS resolver. The MTA-STS policy fetch goes directly from your browser to the target domain. The domains you check never touch Maxinames servers.