Free diagnostics

Free email deliverability tools.

Run focused DNS, authentication, transport-policy, and header checks before you scale a campaign or debug a sending issue.

Run a free checkFull deliverability test

5

free tools

0

stored submissions

No SMTP

mailbox probing

Use the narrowest diagnostic first

Each free tool answers one concrete question. Use it to confirm publication, spot obvious configuration errors, or gather evidence before running a full message test.

  • Use MX lookup when inbound routing or null MX publication is unclear.
  • Use SPF checker before changing sender authorization records.
  • Use DMARC checker before moving policy toward quarantine or reject.
  • Use MTA-STS checker when transport-policy publication matters.
  • Use Header analyzer when you need a private, redacted look at message headers.

Free tools are diagnostics, not delivery guarantees

A clean DNS record or header block does not prove inbox placement. For production sends, pair these checks with a real-message deliverability test, list validation, domain monitoring, and DMARC reporting.

Free tools

MX lookup

Published MX hosts, priority order, and null MX intent.

Use before debugging inbound routing or validating a domain accepts mail.

Run free checkMX records guide

SPF checker

SPF TXT publication, duplicate records, terminal policy, and lookup mechanisms.

Use before changing ESP, CRM, support, or transactional sending records.

Run free checkSPF cheat sheet

DMARC checker

DMARC policy, subdomain policy, percentage, and aggregate reporting.

Use before moving from monitoring to quarantine or reject.

Run free checkDMARC rollout guide

MTA-STS checker

DNS signal, HTTPS policy fetchability, mode, max_age, and MX patterns.

Use when enforcing SMTP TLS policy or debugging transport-policy publication.

Run free checkMTA-STS guide

Header analyzer

Required headers, dates, Message-ID, MIME hints, unsubscribe, and risk signals.

Use when you need private, redacted evidence from a message header block.

Run free checkList-Unsubscribe guide

Related

MX lookup

Check published mail exchange hosts and priority order.

SPF checker

Inspect sender authorization records and common SPF risks.

DMARC checker

Review policy, subdomain policy, percentage, and reporting.

MTA-STS checker

Validate DNS publication and HTTPS policy fetchability.

Header analyzer

Analyze headers with automatic PII redaction.

FAQ

Are these free tools the same as a full deliverability report?

No. They check focused DNS, policy, or header evidence. A full deliverability report uses the actual sent message and evaluates more layers together.

Do the free tools retain submitted domains or headers?

No. The public diagnostics are designed for request-time evidence and no default retention of submitted domains or pasted headers.