mailX by mailwarm (YC S20).

mailX by mailwarm (YC S20)

mailX is a 100% free email deliverability toolkit that instantly diagnoses why your emails land in spam and shows you exactly how to fix it. Powered by live DNS data and trusted by 50,000+ marketers and developers, mailX delivers actionable insights in seconds with zero signup required.

Product Highlights

• Instant DNS Analysis: Run live checks against real DNS records for A, MX, TXT, CNAME, and PTR with immediate results
• Email Authentication Verification: Validate SPF, DKIM, DMARC, and BIMI records to prevent spoofing and boost inbox placement
• Blacklist Monitoring: Scan your domain and IP against RBL/DNSBL databases to catch reputation threats before they impact delivery
• MCP Server Ready: Integrate directly with AI agents via Model Context Protocol for automated deliverability workflows
• Privacy-First Design: No data storage, ever—your domain information stays completely confidential

Use Cases

• Cold Email Campaigns: Validate domain setup before launching outreach to protect sender reputation from day one
• Transactional Email Debugging: Quickly identify DNS or authentication misconfigurations causing delivery failures
• Agency Client Audits: Deliver comprehensive deliverability reports across multiple domains without complex tooling
• AI-Powered Automation: Connect mailX MCP to Claude and other agents for continuous infrastructure monitoring

Target Audience

mailX serves founders launching email programs, sales teams scaling outbound operations, marketers optimizing campaign performance, agencies managing client portfolios, and developers debugging infrastructure—anyone who needs fast, clear answers when deliverability issues arise.