# Postmark: L1 · Needs a person As of 6 Oct 2026, an AI agent can't use Postmark on its own: reCAPTCHA picture challenge on sign-up form. Source: https://agentdrives.com/tools/postmarkapp?via=md · driven 6 Oct 2026 by AgentDrives's agent · Same level in 2 drives in a row · Rules of 15 Oct 2026 (https://agentdrives.com/method/rules?via=md) · license CC BY 4.0 L1 · Needs a person: an agent cannot get itself a working account today. It never got past signup: the invisible reCAPTCHA escalated to a picture challenge. Before that wall, headless docs are unusually complete: llms.txt, an AI catalog, auth.md, and a documented test token that let our agent POST to /email and get a real "Test job accepted" with no account. That token never stores or delivers mail, and tokens for real sends are issued only by a human in the web UI. No plan was ever started, so paying, cancelling, and deleting were never reached. _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 ## 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: llms.txt, AI catalog, RFC 9727 api-catalog, Swagger 2.0 specs for Server and Account API, auth.md, agent-skills index and markdown docs via Accept: text/markdown, all fetched headless. - **Sign up**: Needs a human: Web form only (no sign-up API). Headless POST returns 400 with an empty body; in the browser the invisible reCAPTCHA escalated to a visible picture challenge (crosswalks). - **Verify**: Not reached: Not reached: sign-up never completed. - **Key**: Not reached: Tokens are issued only by a human in the web UI (auth.md); no OAuth, device flow or agent registration. Not reached because sign-up was blocked. - **First call**: Headless: POST /email with the documented test token POSTMARK_API_TEST, no account needed: 200 'Test job accepted'. The test token works only on /email and /email/batch. - **First action**: Not reached: Nothing can be created without a real Server token; test-token sends are accepted but not stored or delivered. - **Pay**: Not reached: Free Developer plan (100 emails/month, never expires). Paid plans: 'Buy Now' goes to the same reCAPTCHA-gated sign-up form; no 402, x402, MPP, UCP or billing API found, and not listed in the x402 Bazaar or mpp.dev. The checkout itself was not seen; the human gate is the reCAPTCHA in front of it. - **Cancel**: Not reached: No plan was started (no account). Account API has no billing endpoints. - **Delete**: Not reached: No account was created. The Account API has no account-delete endpoint; deletion route not tested. ## Does Postmark have an MCP server, and can an agent connect to it? Yes. Postmark has an official MCP server. The server runs on the agent's own machine and lists 24 tools. A new agent can't get in on its own: in the drive of 6 Oct 2026, our agent stopped at sign up (it needs a person). Through the MCP server, 0 of our agent's 1 attempt worked. ## How does an AI agent get a Postmark API key? Not reached: in the drive of 6 Oct 2026, sign-up stopped our agent first (it needs a person). Tokens are issued only by a human in the web UI (auth.md); no OAuth, device flow or agent registration. Not reached because sign-up was blocked. ## Paying the agent way Payment not reached. 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). From the drive of 6 Oct 2026. ## What an agent can do - Read the full docs, OpenAPI, auth.md and Agent Skills without an account - Validate /email and /email/batch request shapes with the test token POSTMARK_API_TEST, without delivering mail ## What it cannot do - Create an account: reCAPTCHA picture challenge on the web-only sign-up form - Get a Server or Account API token: tokens are issued only in the web UI by a human - Send real mail, manage templates, domains, senders, bounces: all need a real token - Run the official MCP server: it exits on startup unless given a real Server token ## Tips for the owner 1. Let verified agents sign up without CAPTCHA 2. Offer a headless path to a Server token 3. Let the MCP server start with the test token 4. Publish OpenAPI 3.x specs 5. Add a billing and account-delete API 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 · [Postmark vs AgentMail](https://agentdrives.com/compare/agentmail-vs-postmarkapp?via=md) - [Mailgun](https://agentdrives.com/tools/mailgun.md?via=md): L1 · Needs a person · [Postmark vs Mailgun](https://agentdrives.com/compare/mailgun-vs-postmarkapp?via=md) - [Mailtrap](https://agentdrives.com/tools/mailtrap.md?via=md): L1 · Needs a person · [Postmark vs Mailtrap](https://agentdrives.com/compare/mailtrap-vs-postmarkapp?via=md) - [Resend](https://agentdrives.com/tools/resend.md?via=md): L1 · Needs a person · [Postmark vs Resend](https://agentdrives.com/compare/postmarkapp-vs-resend?via=md) - [SendGrid](https://agentdrives.com/tools/sendgrid.md?via=md): L1 · Needs a person · [Postmark vs SendGrid](https://agentdrives.com/compare/postmarkapp-vs-sendgrid?via=md) ## Tips for agent builders - Start with POSTMARK_API_TEST: it validates /email and /email/batch shapes without sending; every other endpoint answers 403 ErrorCode 10. - Auth is X-Postmark-Server-Token / X-Postmark-Account-Token headers, never Bearer; 401 ErrorCode 10 is terminal. - Read /auth.md and /.well-known/ai-catalog.json first; the api-catalog links both Swagger specs. - Ask your human for a dedicated server's Server token: sign-up has a reCAPTCHA picture challenge and tokens come only from the UI. - The MCP server needs a real Server token at startup; it will not start with the test token.