mailX
Free DNS lookup and email deliverability toolkit that analyzes domain configuration, authentication records, and identifies why emails land in spam.
🔗 Visit mailX
Description
"Why did my email end up in spam?" is a question that usually requires understanding a handful of obscure DNS records (SPF, DKIM, DMARC, MX) that most people setting up email have never had to touch. mailX is a free, no-signup tool that runs all those checks for you and translates the results into plain English — what's broken, why it matters, and exactly what to fix — instead of leaving you to decode raw DNS output yourself.
mailX bundles SPF, DKIM, DMARC, and BIMI authentication checking, blacklist/DNSBL scanning, general DNS lookups (A, MX, TXT, CNAME, PTR records), SMTP/IMAP testing, a DNS propagation checker, and generators for SPF/DMARC/DKIM records, all wrapped in plain-English explanations rather than raw technical output. It also exposes a JSON API and an MCP server integration, meaning AI agents can query it directly to diagnose a domain's email health as part of an automated workflow — a notable design choice by mailwarm, the team also behind the Mailwarm warmup tool. It's entirely free with no signup required, aimed at founders, marketers, sales teams, agencies, and developers who need to fix deliverability problems without hiring an email infrastructure specialist.
💬 Our review
The short version: mailX takes a genuinely confusing technical problem — decoding SPF/DKIM/DMARC/blacklist status — and makes it free, fast, and readable, which is hard to argue with at this price.
DNS and email-authentication checkers have existed for years (MXToolbox is the long-standing default), but mailX's angle is plain-English remediation guidance plus native support for AI agents via an MCP server and JSON API, which fits how a growing share of technical diagnosis now happens — an agent checking domain health as part of a larger automated task rather than a human manually reading raw DNS output. Being completely free with no signup is a real advantage over tools that gate deeper checks behind an account; the tradeoff is that a free diagnostic tool from a smaller team offers no guarantee of long-term maintenance the way an established, monetized product like MXToolbox does. Worth using anytime you need a quick, readable answer to "why is this domain having email problems"; if you need a permanent, integrated monitoring dashboard rather than an on-demand check, a paid deliverability suite is the better long-term fit.
💰 Pricing
📊 Global score
🤖 AI-enriched data
100% gratuit, aucune inscription requise
Pros
Entièrement gratuit, sans inscription
Explications en langage clair plutôt que sortie DNS brute
Intégration API JSON et serveur MCP pour agents IA
Couvre authentification (SPF/DKIM/DMARC/BIMI), blacklists et DNS en un seul outil
Cons
Outil gratuit d'une petite équipe, pas de garantie de maintenance à long terme
Pas de monitoring continu/alerting intégré, c'est un check à la demande
Moins connu et éprouvé que MXToolbox