What is mailX by mailwarm?

mailX is a free, no-signup email deliverability toolkit that analyzes your domain or IP in seconds. It performs live DNS lookups to check SPF, DKIM, DMARC, MX configuration, blacklist status, and more. Instead of burying you in raw technical data, mailX delivers plain-English explanations of what's wrong and exact steps to fix it. It's built for both humans and AI agents, with an API and MCP server ready out of the box.

Who it's for

• Founders – launching cold email, newsletters, or transactional flows without burning domain reputation.
• Sales teams – scaling outbound campaigns while protecting inbox placement, reply rates, and sender trust.
• Developers – debugging DNS, SMTP, authentication records, and infrastructure issues without jumping between tools.

Key features

One-click combined audit

Run SPF, DKIM, DMARC, MX, and blacklist checks in a single scan. Instead of piecing together results from separate tools, you get one unified report with every deliverability factor analyzed together.

Plain-English explanations and fixes

Every issue comes with a clear, jargon-free description of what it means and exact steps to resolve it. No need to decode raw DNS records or hunt for documentation.

MCP server and JSON API

mailX exposes an MCP server for AI agents and a clean JSON API for engineers. You can integrate deliverability checks directly into your automation workflows, CI/CD pipelines, or AI-powered tools.

Live DNS analysis with zero data storage

All checks run against live DNS data in real time. No data is stored, ever. You get instant, accurate results without worrying about privacy or data retention.

What stands out

"Every tool also exposes an MCP server for AI agents and a clean JSON API."

This is what sets mailX apart from traditional deliverability checkers like MXToolbox. While most tools are designed exclusively for human users, mailX is built from the ground up to serve both people and AI agents. Developers can plug the MCP server into their AI workflows, and the JSON API makes automation straightforward. Combined with the free, no-signup model and instant live DNS analysis, it's a rare combination of accessibility and technical depth.

Worth checking out if…

You send email and want to know exactly why it's landing in spam — without signing up, paying, or deciphering technical jargon. Whether you're a founder debugging your first cold email campaign, a sales team protecting sender reputation at scale, or a developer automating deliverability checks, mailX gives you clear answers and actionable fixes in seconds.