Mail Deliverability Check
Checks a domain’s MX, SPF, DKIM and DMARC records together and explains why mail would be rejected.
Reads everything the DNS says about how a domain sends and receives mail — MX, SPF, DMARC, DKIM keys, MTA-STS, TLS-RPT — in one pass, and says what is missing or contradictory. It is the check to run when your mail is landing in spam and nobody can say why.
DNS lookups only. The domain name goes through our server to a public resolver (Cloudflare); we never connect to the mail servers.
How to use it
Enter the domain after the @
The mail domain, not an address and not a URL. For a subdomain that sends its own mail, check that subdomain separately.
Add the DKIM selector if you know it
DKIM keys live at a selector name that cannot be discovered from DNS. Take the s= value from the DKIM-Signature header of a message you sent; without it, the common names are tried and often miss.
Work through the findings in order
They are tagged by area. Missing SPF and missing DMARC come first; an SPF record over the ten-lookup limit is the subtle one, because it fails as though there were no SPF at all.
Common questions
Does it send a test message?
No. Every answer here comes from DNS records; no mail server is contacted and nothing is delivered anywhere.
DKIM was not found — is it broken?
Probably not. Without the right selector there is nothing to look up, and the selector is not published anywhere. Find it in a sent message’s headers and enter it; a missing key with the correct selector is the real problem.
Everything passes but mail still goes to spam
Authentication is the floor, not the ceiling. Reputation of the sending IP and domain, content, complaint rate and list hygiene all decide placement, and none of them are visible in DNS. What this rules out is the half that is fixable by editing a record.
What is MTA-STS for?
It tells other mail servers to require TLS when delivering to you, which closes the downgrade attack that plain opportunistic TLS leaves open. It is optional, and its absence is a note here rather than a failure.
Feed it from
DNS Lookup
Queries A, AAAA, CNAME, MX, TXT, NS, SOA, SRV, CAA and PTR records over DoH, with TTL and the DNSSEC bit shown, from Cloudflare or Google.
SPF & DMARC Record Builder
Builds valid SPF and DMARC TXT records from a guided form and explains each mechanism it emits.
Email Header Analyser
Parses raw email headers into a delivery timeline with per-hop delays, reads the receiving server’s SPF, DKIM and DMARC verdicts, and flags From/Reply-To/Return-Path mismatches.
Disposable Email
Gives you a throwaway inbox that receives mail for a limited time, with attachments viewable in place.
Next
These accept what this tool produces, so the result can go straight in.
SPF & DMARC Record Builder
Builds valid SPF and DMARC TXT records from a guided form and explains each mechanism it emits.
DNS Lookup
Queries A, AAAA, CNAME, MX, TXT, NS, SOA, SRV, CAA and PTR records over DoH, with TTL and the DNSSEC bit shown, from Cloudflare or Google.
Email Header Analyser
Parses raw email headers into a delivery timeline with per-hop delays, reads the receiving server’s SPF, DKIM and DMARC verdicts, and flags From/Reply-To/Return-Path mismatches.
Disposable Email
Gives you a throwaway inbox that receives mail for a limited time, with attachments viewable in place.
HTTP Request Builder
Composes and sends a GET/POST/PUT/PATCH/DELETE/HEAD request with custom headers and a body, and shows the status, headers, body and timing — without ever forwarding cookies or Authorization.
Barcode Generator
Generates EAN-13, UPC, Code128, Code39 and ITF barcodes with check digits and print-ready output.