mailX

Perform immediate spam, DNS, and email authentication checks.

Paidthemailx.comJun 5, 2026

Combined Deliverability Audit

Runs SPF, DKIM, DMARC, MX, and blacklist checks together for a domain or IP, returning one prioritized report with actionable findings.

Live DNS & Mail Server Toolkit

Provides DNS lookup, propagation checks, MX, TXT, CNAME, PTR queries, SMTP/IMAP tests, and generators for SPF, DKIM, and DMARC records built on real‑time DNS data.

Plain‑Language Explanations

Translates dense authentication details into short, understandable descriptions and copy‑paste‑ready DNS records, so non‑specialists can correct issues quickly.

MCP & JSON API for AI Agents

Exposes each checker and a higher‑level deliverability audit through an MCP server and JSON responses, enabling agents and developer tools to call diagnostics programmatically.

No‑Signup Instant Access

All core DNS and deliverability checks are available immediately from the browser without registration or payment.

Blacklist Monitoring

Checks a domain or IP against common email blacklists, surfacing reputation problems that undermine deliverability.

What is mailX?

mailX is a free email deliverability and DNS diagnostic toolkit that helps teams understand why emails land in spam and how to fix the underlying technical issues. It combines live DNS lookups, SPF, DKIM, DMARC, and blacklist checks with clear, human‑readable guidance. Both humans and AI agents can run audits in seconds from the browser, a JSON API, or an MCP server.

Core Features

Combined Deliverability Audit: Runs SPF, DKIM, DMARC, MX, and blacklist checks together for a domain or IP, returning one prioritized report with actionable findings.
Live DNS & Mail Server Toolkit: Provides DNS lookup, propagation checks, MX, TXT, CNAME, PTR queries, SMTP/IMAP tests, and generators for SPF, DKIM, and DMARC records built on real‑time DNS data.
Plain‑Language Explanations: Translates dense authentication details into short, understandable descriptions and copy‑paste‑ready DNS records, so non‑specialists can correct issues quickly.
MCP & JSON API for AI Agents: Exposes each checker and a higher‑level deliverability audit through an MCP server and JSON responses, enabling agents and developer tools to call diagnostics programmatically.
No‑Signup Instant Access: All core DNS and deliverability checks are available immediately from the browser without registration or payment.
Blacklist Monitoring: Checks a domain or IP against common email blacklists, surfacing reputation problems that undermine deliverability.

Use Cases & Considerations

Use Cases

Founders & Indie Builders Validating New Domains: Before scaling cold email, newsletters, or transactional systems, run a quick audit to confirm DNS and authentication are correctly configured and emails won’t go to spam.
Sales & SDR Teams Fixing Reply Rates: Verify sender domains and troubleshoot technical issues that quietly reduce deliverability; apply the plain‑language fix instructions to boost reply rates.
Marketing & Growth Teams Auditing Multiple Domains: Audit authentication records across marketing automation, CRM, and lifecycle messaging domains in one place, ensuring consistent deliverability.
Agencies & Deliverability Consultants: Perform fast multi‑domain audits for clients and produce clear, shareable DNS fix lists that even non‑technical stakeholders can implement.
Developers & DevOps Engineers Debugging Configurations: Debug DNS, SMTP, and IMAP issues using live lookups and tests, replacing a stack of single‑purpose utilities with one toolkit.
AI Agent Builders Integrating Live Checks: Give autonomous agents an MCP skill for real‑time SPF, DKIM, DMARC, and blacklist checks inside larger workflows.

Limitations & Considerations

Diagnostic‑only focus: mailX does not include email sending, warm‑up, or inbox placement tracking; you still need separate tools for outreach and warm‑up.
No long‑term deliverability analytics: The tool provides snapshot checks, not ongoing dashboards for deliverability trends or engagement metrics.
API and MCP require scripting knowledge: While powerful, using the API or MCP server assumes some development comfort; non‑technical teams may find the docs developer‑oriented.
Consulting pricing is opaque: The “SOS I Land in SPAM” expert help lacks transparent per‑session or subscription pricing, making it hard to budget without contacting support.
No scheduled monitoring or alerts: You must manually re‑run checks—mailX doesn’t monitor domains continuously or notify you of configuration changes.
Limited advanced authentication checks: Core SPF/DKIM/DMARC/MX are well covered, but it may not check emerging standards like BIMI, MTA‑STS, or DANE.

How to use mailX

Open your browser and go to themailx.com – no sign‑up is required for core diagnostics.
Choose the check you need: click “Deliverability Audit” for a combined report, or pick individual tools like DNS lookup, SPF check, or blacklist scan.
Enter the domain (e.g., example.com) or IP address you want to diagnose and start the check.
Review the results: a prioritized list of issues appears with plain‑language explanations and copy‑paste‑ready DNS record fixes.
Apply the suggested changes through your DNS hosting provider and, when needed, use the propagation checker to confirm updates have taken effect globally.
For automation, call the JSON API or connect the MCP server to integrate checks directly into your scripts, CI/CD pipelines, or AI agents.

Pricing & Plans

mailX offers its core diagnostic tools—DNS lookups, combined deliverability audits, blacklist checks, and DNS record generators—completely free, with no account or signup required. This includes unlimited use through the web app, API, and MCP server. For users who want personalized help, the “SOS I Land in SPAM” option connects you with a deliverability expert; however, pricing for that consulting service is not publicly listed on the website. Always refer to the official mailX website for the most current pricing details, as the information may change.

Platforms

Web application: Accessible on any modern browser at themailx.com, with no installation required and a responsive design that works on mobile.
JSON API: All checks can be triggered programmatically via REST endpoints that return JSON, suitable for scripts and integrations.
MCP (Model Context Protocol) server: Provides an interface for AI agents and tools to run diagnostics as an MCP skill, enabling natural language‑driven audits.
No dedicated mobile app – but the web interface adapts well to phones for quick checks on the go.

Tips & Best Practices

Run an audit before launching any campaign: Pre‑validate domains to catch missing SPF, misaligned DKIM, or weak DMARC policies that could land emails in spam.
Use the copy‑paste records: The tool generates exact DNS entries for SPF, DKIM, and DMARC—paste them directly into your DNS manager to avoid typos.
Repeat checks after making DNS changes: The live lookup and propagation checker help you confirm that fixes are active worldwide.
Integrate into CI/CD or monitoring scripts: With the API and MCP, automate periodic deliverability audits to catch regressions early.
Check blacklists proactively: Even with perfect authentication, a domain or IP may be blacklisted; a quick scan uncovers reputation issues before they hurt campaigns.
Share the human‑readable report with non‑technical stakeholders: Plain‑language explanations help founders, marketers, and clients understand issues without deep DNS knowledge.

Who is mailX for?

Founders and indie builders who need to validate email deliverability quickly without diving into complex DNS tools.
Sales development reps (SDRs) and outbound teams wanting to ensure their sender domains are configured correctly to maximize reply rates.
Marketing and growth professionals managing multiple domains across automation, CRM, and lifecycle email platforms.
Agencies and deliverability consultants performing fast multi‑domain audits for clients and generating easy‑to‑follow fix instructions.
Developers and DevOps engineers debugging email‑related DNS, SMTP, and IMAP issues with a single toolkit.
AI agent developers looking to give their agents live SPF, DKIM, DMARC, and blacklist checking capabilities via an MCP server or JSON API.

Alternatives

View all

MXToolbox

Broad DNS and email health checks with many lookup tools, but lacks plain‑language guidance and native MCP/AI‑agent support.

DNSChecker

Simple DNS propagation and lookup tool without combined deliverability audits, blacklist checks, or agent integrations.

EasyDMARC

Specializes in DMARC monitoring and reporting with in‑depth analytics, but requires signup and isn’t instantly free for all checks.

GlockApps

Provides inbox placement testing and deliverability monitoring dashboards, but focuses on sending and warm‑up rather than pure diagnostics.

LeafDNS

Quick SPF/DKIM/DMARC validator with simple explanations, but no API or MCP server for programmatic use.

PowerDMARC

Enterprise‑grade DMARC suite with detailed reporting and alerting, overkill for rapid one‑off domain audits and not agent‑first by design.

FAQ

Q1. Do I need to create an account to use mailX?

No. All core DNS lookups, deliverability audits, blacklist checks, and DNS record generators are available instantly without signup or payment.

Q2. Can AI agents or LLMs use mailX programmatically?

Yes. mailX provides both an MCP (Model Context Protocol) server and a JSON API, allowing AI agents to run SPF, DKIM, DMARC, blacklist checks, and combined audits and interpret the results.

Q3. Does mailX send test emails or warm up my domain?

No. mailX is purely diagnostic. It does not send emails or manage inbox warm‑up. You will need a separate sending or warm‑up service for those tasks.

Q4. How is mailX different from MXToolbox?

While both perform DNS lookups, mailX combines multiple checks into a single prioritized report with plain‑language fix guidance and also offers an MCP/API for AI agents—something MXToolbox doesn’t provide.

Q5. Is the “SOS I Land in SPAM” help free?

No, that service connects you with a deliverability expert and is a paid offering. Pricing details are not publicly listed; contact mailX directly for a quote.