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MailX

Vendor: MailX

MailX is a free email deliverability and DNS toolkit that checks SPF, DKIM, DMARC, blacklists, and mail servers, with API and MCP access.

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linkedin email Marketers diagnosing email deliverability issues Developers integrating DNS checks into automation workflows Sales teams verifying sender reputation before campaigns #email-deliverability #dns-toolkit #spf-checker #dmarc-validator #blacklist-checker #api-access #free-tool

Overview

MailX is a free toolkit for diagnosing email deliverability and DNS problems. Entering a domain runs live checks across DNS records, SPF, DKIM, DMARC, BIMI, MX configuration, blacklist status, and SMTP or IMAP connectivity, then returns a report that explains each issue in plain language along with the specific fix. Every tool queries live DNS in real time and none require a signup or account, which makes the suite usable for quick one-off diagnostics as well as routine audits. Beyond the browser interface, the same checks are exposed through a JSON API and an MCP server, so scripts and AI agents can run them programmatically. mailX is published by the team behind Mailwarm and states that more than 50,000 marketers and developers use the tools.

Key Features

Combined Deliverability Audit

Runs SPF, DKIM, DMARC, MX, and blacklist checks together in one pass and returns a single consolidated report.

Authentication Checkers

Individual SPF, DKIM, DMARC, and BIMI validators that explain failures without requiring the user to read raw records.

DNS Lookup Suite

A, MX, TXT, CNAME, and PTR lookups alongside a DNS checker and a propagation checker.

Mail Server Testing

SMTP and IMAP tests and finders that check connectivity, configuration, and response time.

Record Generators

SPF, DMARC, DKIM, and general DNS record generators sit next to the checkers so flagged problems can be fixed immediately.

API and MCP Access

A JSON API and an MCP server allow the same checks to run inside automations, CI pipelines, or AI agents.

Pros & Strengths

  • ✓
    Free With No Signup: Every check runs without an account, which removes the friction of one-off diagnostics during an incident.
  • ✓
    Consolidated Audit: Authentication, DNS, and blacklist checks run together instead of being stitched together from several single-purpose sites.
  • ✓
    Plain-Language Output: Results explain what is broken and how to fix it rather than returning raw record dumps.
  • ✓
    Generators Beside Checkers: SPF, DKIM, and DMARC generators sit alongside the validators, so a flagged issue can be corrected in the same session.
  • ✓
    Agent and Script Friendly: The JSON API and MCP server make the toolkit usable inside automations and AI workflows, not just the browser.
  • ✓
    Live Results: Checks query live DNS in real time rather than returning cached lookups.

Cons & Tradeoffs

  • ⚠
    Diagnostics Only: The toolkit identifies problems but does not warm up mailboxes, send email, or remediate anything on the user's behalf.
  • ⚠
    No Saved History: With no accounts, reports are not stored, so changes cannot be compared between checks over time.
  • ⚠
    No Monitoring or Alerts: Checks are run on demand rather than watching a domain continuously and flagging regressions.
  • ⚠
    Configuration, Not Placement: The tools verify authentication and blacklist status rather than testing where messages actually land across providers.
  • ⚠
    Undefined Paid Support: Help beyond the free tools runs through a booked call with no published scope or pricing.

Known Limitations

  • • No account system means reports are not stored or compared over time
  • • On-demand checks only; no continuous monitoring or alerting capabilities
  • • Focuses on DNS and authentication rather than actual inbox placement testing

Pricing & Plans

Model: free

All tools are offered free of charge with no signup, account, or credit card required. The company also offers booked consultation services for teams whose mail is landing in spam, with scope and pricing available upon contact.

✓ Free Plan ✓ Free Trial

Editorial Info

Last Reviewed: 2026-08-20

Verified Sources & Research

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