Email-sending domain health, in one shot
Instant MX, SPF, DKIM, DMARC, blacklist, and TLS diagnostics. No signup. Modern, fast, transparent.
Email deliverability fails for many reasons, and most of them start in DNS. Relaymetry checks the technical signals receivers like Gmail, Outlook, and Yahoo actually weigh: MX, SPF, DKIM, DMARC, blacklist presence, and SMTP TLS posture. One report, no account, plain English. Authentication that passes here will not guarantee an inbox placement, but a domain that fails here is almost certainly losing mail.
Run individual checks
- MX lookupLook up MX records for any domain. Instant, free, plain English.
- SPF CheckerCheck a domain's SPF record — syntax, lookup count, and common issues. Instant, free, plain English.
- DKIM CheckerCheck a DKIM public key for a given domain and selector. Instant, free, plain English.
- DMARC CheckerCheck a domain's DMARC policy — what it enforces, what's missing, and where it aligns. Instant, free, plain English.
- Blacklist lookupCheck whether your mail-server IPs are listed on email blacklists. Instant, free, plain English.
- TLS CheckInspect both your domain's outbound submission server TLS and the inbound TLS posture announced via DNS (MTA-STS + TLS-RPT). Instant, free, plain English.
- SPF GeneratorBuild a valid SPF record in seconds. Pick your senders, set the policy, copy the TXT record.
- DMARC GeneratorBuild a DMARC record in seconds. Pick a policy, add a reporting address, copy the TXT record for _dmarc.
- DKIM GeneratorGenerate a DKIM keypair in your browser. Copy the public DNS record; the private key never leaves this page.
- Header AnalyzerPaste raw message headers. See the delivery path, per-hop delays, and the SPF / DKIM / DMARC verdicts the receiving server recorded. Headers never leave your browser.
- DMARC Report AnalyzerUpload or paste a DMARC aggregate (RUA) report. See pass rates, per-source breakdowns, and actionable findings. Your report never leaves your browser.
- TLS-RPT Report AnalyzerPaste or upload an RFC 8460 SMTP TLS (TLS-RPT) report. See per-policy success and failure session counts, an aggregate TLS success rate, and plain-English failure reasons. Your report never leaves your browser.
- Reverse DNS LookupLook up the PTR record for an IP and confirm it forward-resolves back to the same address. Instant, free, plain English.
Diagnose deliverability issues
Why Gmail rejects emailsWhy emails get rejected or land in spam, with step-by-step diagnosticsFree SPF & DMARC checkers comparedHow these tools differNeed checks programmatically? API early access →
What email-sending domain health actually means
Email-sending domain health is the combined state of how your domain authenticates outbound mail and what receivers can verify about you from public DNS records. It includes the records that route inbound mail (MX), the records that authorize outbound senders (SPF), the cryptographic signature on each message (DKIM), the policy that ties them together for receivers (DMARC), the blocklists your IP or domain might appear on, and the TLS posture your mail servers advertise. Receivers grade these signals on every message.
What Relaymetry checks now
MX records — the hostnames that accept inbound mail for your domain. SPF — the TXT record that lists who is allowed to send as your domain. DKIM — the published public keys that verify a sending server signed the message. DMARC — the policy that tells receivers what to do when SPF or DKIM fail to align with the visible From-domain. Blocklists — public DNSBL zones that flag IPs or domains observed sending unwanted mail. TLS — the encryption posture for SMTP connections, including MTA-STS and TLS-RPT.
What Relaymetry does not promise
A clean report is not a promise of inbox placement. Receivers also weigh sender reputation, complaint and bounce rates, message content, recipient engagement, and signals from their own anti-abuse systems — none of which are visible from public DNS. Authentication that passes can still be filtered to spam by reputation and content scoring. We surface the technical baseline; we do not run inbox-placement seed tests, monitor sender reputation over time, or ingest DMARC aggregate reports in this release.
Who this is for
Built for sysadmins, IT leaders, SMB founders launching a new domain, deliverability consultants triaging a client, and MSP teams answering "is our mail working" questions. No account, no upsell, no tracking beyond aggregate page analytics.