Let Agents In

Agent readiness · Transactional email APIs

mailgun.com

9 of 14 measurable points under formula 9.2, measured on 2026-08-12. 15 checks exist; each is one HTTP request with a published rule, so every sentence below can be rerun and argued with. 1 of them could not be measured from where we ask, and those are left out of the denominator rather than counted as failures.

A · Discovery

  • PASS
    Answers an agent user-agentAnswered 200 to LetAgentsIn/1.0 (+https://letagentsin.com/methodology)
  • PASS
    llms.txt publishedllms.txt present at https://documentation.mailgun.com/llms.txt, and the 12 links we sampled across the file all answer
  • PASS
    Docs readable without JavaScript10,570 characters of text without JS, on https://documentation.mailgun.com/docs/mailgun/user-manual/api-key-mgmt/rbac-mgmt rather than on https://documentation.mailgun.com/docs/mailgun/sdk/introduction
  • PASS
    On-demand agents not blockedNo on-demand agent is blocked
  • N/A
    Paths robots.txt points at answerrobots.txt names no concrete path, only patterns or nothing, so there is no claim to check
  • PASS
    No punishing crawl delayNo Crawl-delay applies to the agents we check

B · Agent entry

  • UNMEASURED
    Agent entry pointUnmeasurable: 8 of the 9 known agent entry paths answered with a refusal rather than a file or a 404, so what you publish there is not something we measuredLet ordinary HTTP reach these paths and this becomes measurable.
  • FAIL
    OAuth dynamic client registrationNo OAuth metadata on any of the 9 hosts probed, including the usual auth and api subdomains
  • FAIL
    MCP surfaceMCP mentioned 2x in your own files, but nothing answered at mcp.mailgun.com, mcp.mailgun.com/mcp, mcp.mailgun.com/v1/mcp, api.mailgun.com/mcp, /mcp or /api/mcp

C · Registration

  • FAIL
    No CAPTCHA in the signup HTMLrecaptcha appears in the signup page's server HTML, even though the form itself is assembled by JavaScript
  • FAIL
    Signup reachable without a browserhttps://signup.mailgun.com/new/signup is reachable, but its form needs JavaScript

D · Provisioning

  • PART
    Programmatic key provisioning1 of 7 provisioning phrases across the 5 documents we read: "account api"
  • PASS
    Free tier or no-card trial stated in textFree tier or no-card signals at https://www.mailgun.com/pricing/: "Free plan", "free trial", "Try for free"

E · Integration

  • PASS
    Typed SDK on the registrymailgun.js@14.0.0 ships types, matched from the registry by who publishes it rather than by a link on your site
  • PASS
    Machine-readable API descriptionDocs serve markdown to machines, at https://documentation.mailgun.com/docs/mailgun/sdk/introduction.md

Tell me when this changes

The failures here are the kind nobody notices. An edge rule that starts refusing agents changes nothing a person sees in a browser, so the first sign is usually an integration that quietly stopped working. We rescan weekly and write only when a verdict moves.

This page is the newest scan we hold for mailgun.com and changes when we rescan. It is not a judgement of the product: we measure whether an unattended run can get through, not whether the thing is any good. The whole corpus is published as JSON and CSV.

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