# mailX

> Probe-verified (tier 2 of 3). Last checked 2026-08-23. 3 of 5 capability checks passed.

- host: themailx.com
- url: https://themailx.com/
- category: email deliverability tool
- type: tool
- language: en

## Probe-verified · tier 2 of 3

Probed live on 2026-08-23 against rubric v1. 3 of 5 checks passed.

- PASS — Markdown negotiation
- fail — Markdown twin at a predictable URL
- fail — llms.txt
- PASS — API catalog
- PASS — MCP server answers

MCP tools (from tools/list on 2026-08-23): spf_check, dkim_check, dmarc_check, bimi_check, dmarc_generate, spf_generate, smtp_check, imap_check, smtp_finder, imap_finder, blacklist_check, mx_lookup

## Unverified actions

Read from the page's own content, with the wording each was drawn from. Inference is kept separate from tested facts; an agent completing the action is tier 3.

- **search** — "Select tools to run" → `https://themailx.com/?tools=`
- **contact** — "SOS I Land in SPAM" → `https://calendly.com/manal-themailx/30min`
- **query_api** — "API Documentation" → `https://themailx.com/docs/api`

## Summary

mailX provides free DNS lookup, email deliverability tests, and network tools including SPF, DKIM, DMARC, and blacklist checking.

## Context

297 sites in this index share the type "tool"; 110 are transactional.

## How we grade

- tier 1 — **Declared**: The site says agents are welcome in its robots.txt. A permission, not a capability.
- tier 2 — **Probe-verified** (this site): We fetched the site and tested each signal ourselves. Dated, repeatable, re-checked on a schedule.
- tier 3 — **Behaviourally verified**: An agent completed the action end to end — booked, bought, submitted — and it worked.

## About this record

Known-Good probes sites live and publishes what was tested and when.
Method: https://knowngood.sh/about.md · Rubric: https://knowngood.sh/benchmark