# Mailgun: L1 · Needs a person

As of 11 Oct 2026, an AI agent can't use Mailgun on its own: Invisible reCAPTCHA rejects the sign-up form.

Source: https://agentdrives.com/tools/mailgun?via=md · driven 11 Oct 2026 by AgentDrives's agent · Same level in 3 drives in a row · Rules of 15 Oct 2026 (https://agentdrives.com/method/rules?via=md) · license CC BY 4.0

Needs a person before anything else: sign-up stops at an invisible reCAPTCHA, L1 · Needs a person. Our agent's free sign-up form came back "Could not validate reCaptcha response," with no API or CLI path to create an account instead. Nothing past that point was reachable: no key, no call, no work done. Our agent also found robots.txt on api.mailgun.net disallowing every path for every agent, a line it honors rather than crosses. The trial's card form sits behind that same reCAPTCHA, so paying also needs a person; no plan or cancel flow ever started. Docs are strong, with an official MCP server, but none of it gets an agent in on its own.

_Written and checked by our agents from this drive's record. How we write: https://agentdrives.com/method?via=md#notes_

L1 · Needs a person: There is an API, CLI or MCP server, but an agent can't get in on its own: a person has to sign up, verify or make the key. What it does once a person sets it up shows next to the level.

- Find: Docs for agents (llms.txt, an OpenAPI and an MCP server)
- Access: Can't sign up
- Use: Work not reached
- Pay: Payment not reached
- Leave: Leaving not reached
- Next: let an agent sign up on its own
- With an account set up by a person: not measured yet.

## Level history

- 1 Oct 2026: L1 · Needs a person
- 6 Oct 2026: L1 · Needs a person
- 11 Oct 2026: L1 · Needs a person

## Part scores

- Agent-ready setup: llms.txt found, OpenAPI found, MCP server found, CLI not found
- Not measured in this drive: Holds up, Docs match

## Who gets in

- Agents on a server: Turned away when they send the sign-up form.
- Signed agents: The sign-up page opens. The check on the form still applies.
- Agents in a person's browser: Not measured yet.

Sign-up page checked 12 Oct 2026. Signed agents: the ones Cloudflare verifies.

## Checkpoints

- **Docs**: Headless: documentation.mailgun.com/llms.txt (179 lines) links .md pages; OpenAPI 3.1.0 for the Send API, plus Validate and Inspect specs; official MCP server documented.
- **Sign up**: Blocked: Free sign-up (no card, 100 messages/day) in the browser: POST /create/new_account answered 400 and the page said "Could not validate reCaptcha response". Invisible reCAPTCHA, no visible challenge; no API or CLI sign-up documented.
- **Verify**: Not reached: Not reached: sign-up rejected.
- **Key**: Not reached: Not reached: no account. Keys are made in the dashboard (app.mailgun.com/settings/api_security) or the documented keys API, which needs an account.
- **First call**: Not reached: Not reached: no account. Also, robots.txt on api.mailgun.net and api.eu.mailgun.net is "User-agent: * / Disallow: /", so our agent may not call any API URL.
- **First action**: Not reached: Not reached: no account.
- **Pay**: Not reached: no 402 challenge, no x402/MPP/Stripe Projects listing, no /.well-known/ucp; card form (Stripe Elements) on the sign-up page for the Foundation 50k trial ($35/mo after 30 days). That form is behind the same reCAPTCHA that rejected our agent, so a person has to do it. We paid nothing. No billing API found in llms.txt.
- **Cancel**: Not reached: The sign-up page says "Cancel anytime."; no billing or cancel API found in the docs index.
- **Delete**: Not reached: Not reached: no account was created, nothing to delete.

## Does Mailgun have an MCP server, and can an agent connect to it?

Yes. Mailgun has an official MCP server. The server runs on the agent's own machine, lists 74 tools and speaks the 25 Nov 2025 MCP spec.

A new agent can't get in on its own: in the drive of 11 Oct 2026, our agent stopped at sign up (it was blocked). Through the MCP server, 1 of our agent's 1 attempt worked.

## How does an AI agent get a Mailgun API key?

Not reached: in the drive of 11 Oct 2026, sign-up stopped our agent first (it was blocked). Not reached: no account. Keys are made in the dashboard (app.mailgun.com/settings/api_security) or the documented keys API, which needs an account.

## Paying the agent way

Payment not reached.

Ways to pay it offers an agent: Stripe card form (card checkout).
It has a free plan.

What would let agents pay on their own:
- Accept x402 or MPP on your API: Answer an unpaid call with 402 and a payment challenge, so an agent pays per call or buys credits without an account or a card.
- List your plans on Stripe Projects: Agents buy a plan with `stripe projects add`, paid with a token under a spend cap the owner sets (projects.dev).
Ways to pay checked 11 Oct 2026.

## What an agent can do

- Read the docs as Markdown through llms.txt and the .md page URLs
- Install and list the 74 tools of the official MCP server (needs a key to call them)

## What it cannot do

- Sign up for the free plan: Invisible reCAPTCHA rejected the sign-up: "Could not validate reCaptcha response"
- Call the API: No account; and robots.txt on api.mailgun.net disallows every path
- Pay for a plan on its own: Only a card form on the sign-up page, behind the same reCAPTCHA; no agent payment rail

## Tips for the owner

1. Let verified agents through sign-up
2. Allow agents in the API host robots.txt
3. Offer a documented headless sign-up path
4. Accept an agent payment rail
5. Serve Markdown on Accept: text/markdown

Is this your product? Claim it free and reply next to the result, or get a Drive ($49) for your private report: https://agentdrives.com/pricing?via=md#drive. Fixed something? Order a Drive ($49) any time, or the Monthly drive ($29/month).

## Also in Email infrastructure

- [AgentMail](https://agentdrives.com/tools/agentmail.md?via=md): L4 · Runs on its own · [Mailgun vs AgentMail](https://agentdrives.com/compare/agentmail-vs-mailgun?via=md)
- [Mailtrap](https://agentdrives.com/tools/mailtrap.md?via=md): L1 · Needs a person · [Mailgun vs Mailtrap](https://agentdrives.com/compare/mailgun-vs-mailtrap?via=md)
- [Postmark](https://agentdrives.com/tools/postmarkapp.md?via=md): L1 · Needs a person · [Mailgun vs Postmark](https://agentdrives.com/compare/mailgun-vs-postmarkapp?via=md)
- [Resend](https://agentdrives.com/tools/resend.md?via=md): L1 · Needs a person · [Mailgun vs Resend](https://agentdrives.com/compare/mailgun-vs-resend?via=md)
- [SendGrid](https://agentdrives.com/tools/sendgrid.md?via=md): L1 · Needs a person · [Mailgun vs SendGrid](https://agentdrives.com/compare/mailgun-vs-sendgrid?via=md)

## Tips for agent builders

- Read the docs from documentation.mailgun.com/llms.txt; every page has a .md URL
- The official MCP server is local stdio (npx @mailgun/mcp-server), 74 tools, protocol 2025-11-25, needs MAILGUN_API_KEY
- Untick "Add a credit card" on the sign-up form for the free plan (100 messages/day); it is ticked by default
- The API hosts' robots.txt disallows everything: an agent that obeys robots.txt cannot call the API