{ "data": { "a": { "slug": "mailpace", "name": "MailPace", "vendor": "OhMySMTP Ltd", "vendorUrl": "https://mailpace.com", "kind": "http-api", "category": "email", "summary": "MailPace is a UK transactional email service, formerly OhMySMTP, hosted in the EU. It sends mail through an HTTPS API or SMTP, turns inbound mail into webhooks and has a Domains and Email Status API.", "url": "https://www.anchorterminal.com/tools/mailpace", "markdownUrl": "https://www.anchorterminal.com/tools/mailpace.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/mailpace.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/mailpace.json", "dns": "mailpace.grade.anchorterminal.com", "repo": "https://github.com/mailpace/mailpace-mcp", "transports": [ "http" ], "packages": [ { "registry": "npm", "name": "@mailpace/mailpace.js" } ], "auth": "api-key", "authNotes": "Each domain has its own server token, sent in the `MailPace-Server-Token` header, which can send from that domain and read its email status. An organisation token in `MailPace-Organization-Token` manages domains and domain tokens through the Domains API, including revoking them. Both are made in the dashboard after a browser signup.", "pricing": "paid", "pricingNotes": "$10 a month includes 10,000 emails sent or received, then $1 per 1,000, per the Paddle prices the pricing page loads and the comparison pages ($100 for 100,000, $1,000 for 1 million). A free plan of up to 100 emails a month is given on request by email. Paddle is the merchant of record; card, PayPal, Apple Pay or Google Pay.", "priceSummary": "$10 / mo", "where": "local", "x402": { "level": "no", "evidence": "No x402, MPP or L402 in the docs repository, the pricing page or the MCP server source (checked 2026-11-06). Payment is by Paddle subscription; the FAQ says crypto isn't accepted.", "endpoints": [] }, "toolCount": 12, "popularity": { "githubStars": 1, "npmWeekly": 207, "pypiWeekly": null, "asOf": "2026-11-06" }, "docsUrl": "https://docs.mailpace.com/", "capabilities": [ "email.send", "email.inbound", "email.domains", "email.analytics" ], "tags": [ "hosted", "closed-source", "smtp", "webhooks", "idempotency", "status-page", "sla", "eu", "mcp", "typescript", "ruby", "go", "php" ], "lastRelease": "2026-10-22", "graded": true, "anchor": { "graded": true, "score": 58.4, "grade": "C", "agentReady": false, "rank": 750, "ranked": true, "rankOf": 1486, "categoryRank": 17, "methodology": "0.7", "run": "2026-10-01", "scores": { "ergonomics": 71, "maintenance": 65, "payments": 25, "reliability": 70, "schema": 54, "security": 50, "transparency": 75 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-11-06" }, "negative": 0, "verdict": "A small transactional sender with idempotent sends, signed webhooks, a 99% availability promise in its terms and a public Upptime status record. There is no OpenAPI spec, no published rate limit, no llms.txt, and its MCP server was rewritten on 4 November 2026 but isn't on npm or in the MCP registry yet.", "bestFor": "Low-volume transactional mail from EU-hosted infrastructure with idempotent sends and no tracking.", "strengths": [ "Sends accept an `Idempotency-Key` header kept for 24 hours, so a retry after a timeout doesn't send twice", "Per-domain server tokens limit a leaked key to one domain, and organisation tokens can create and revoke them by API", "Webhooks are signed with Ed25519 and inbound mail is retried five times before it fails", "Status page on Upptime with GitHub issues as incident reports, and a 99% monthly availability promise with credits in the terms", "Sub-processors and their locations are listed, and mail is kept 30 days plus 7 in backups per the DPA" ], "weaknesses": [ "No OpenAPI spec, llms.txt or Markdown docs for agents; the reference is Docusaurus pages", "Rate limits aren't published; the docs say they vary by organisation age, plan and history", "No free plan without emailing support, and the paid plan starts at $10 a month", "MCP server 2.0.0 exists only in the repository; npm and the MCP registry had nothing for it on 6 November 2026", "No security.txt, disclosure policy or certification found" ], "agentNotes": [ "Send a UUID in `Idempotency-Key` on every `POST /api/v1/send`, and reuse it on a retry; keys last 24 hours and are tied to one token", "Use the server token of the sending domain, since the From domain must match the token's domain or the API returns 403", "On 429 `You are sending emails too quickly` back off; no Retry-After is documented", "Send only transactional mail; marketing and bulk newsletters are prohibited by the docs and terms", "Read delivery with `GET /api/v1/domains/:domain_id/emails/:id` using the id the send returned" ], "metrics": { "kind": "remote", "measured": false }, "reviewCount": 0, "avgRating": 0, "history": [ { "basis": "public evidence", "confidence": "medium", "grade": "C", "methodology": "0.7", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 58.4 } ], "editorialScores": { "ergonomics": 71, "maintenance": 65, "payments": 25, "reliability": 70, "schema": 54, "security": 50, "transparency": 69 }, "provenanceScore": 81, "checked": { "categories": { "ergonomics": "2026-11-06", "maintenance": "2026-11-06", "payments": "2026-11-06", "reliability": "2026-11-06", "schema": "2026-11-06", "security": "2026-11-06", "transparency": "2026-11-06" }, "last": "2026-11-06", "oldest": "2026-11-06", "stale": false, "staleAfterDays": 90 } }, "connect": { "http": "curl https://app.mailpace.com/api/v1/send -X POST -H \"Accept: application/json\" -H \"Content-Type: application/json\" -H \"MailPace-Server-Token: $MAILPACE_TOKEN\" -H \"Idempotency-Key: $(uuidgen)\" -d '{\"from\":\"you@yourdomain.com\",\"to\":\"person@example.com\",\"subject\":\"Hello\",\"textbody\":\"Hello\"}'" }, "letme": { "capability": "https://letme.dev/email.send", "tool": "https://letme.dev/mailpace" }, "area": "communication", "unitPrices": [ { "item": "Scaling plan", "unit": "month", "usd": 10, "note": "includes 10,000 emails sent or received" }, { "item": "Emails beyond 10,000", "unit": "1k-emails", "usd": 1 } ], "provenance": { "legalEntity": "OhMySMTP Ltd", "domain": "mailpace.com", "domainRegistered": "2022-01-10", "endpointOnVendorDomain": true, "terms": "https://mailpace.com/terms", "privacy": "https://mailpace.com/privacy", "statusPage": "https://status.mailpace.com", "changelog": "https://mailpace.com/category/changelog", "securityTxt": "none", "checked": "2026-11-06", "notes": [ "The terms and privacy policy name OhMySMTP Ltd, incorporated in England and Wales, company number 13200428. Companies House lists two active directors.", "Terms last updated 9 January 2026, privacy policy 30 August 2026, DPA updated in October 2026 per the landing repository.", "mailpace.com/robots.txt allows all paths. The terms contain no clause on automated access to the website beyond the usual licence limits.", "RDAP gives mailpace.com a registration date of 10 January 2022; the service ran as OhMySMTP before that.", "/.well-known/security.txt returns 404 on mailpace.com and app.mailpace.com." ], "score": 81 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/mailpace.json", "live": { "slug": "mailpace", "vendorStatus": { "page": "https://status.mailpace.com", "indicator": "unknown", "summary": "no machine-readable status found", "checkedAt": "2026-11-07T04:48:01.553362214Z" }, "versions": [ { "registry": "npm", "name": "@mailpace/mailpace.js", "version": "0.1.3", "seenAt": "2026-11-06T23:42:02.752996422Z" } ], "githubStars": 1, "npmWeekly": 207, "securityTxt": { "url": "https://mailpace.com/.well-known/security.txt", "state": "none", "checkedAt": "2026-11-07T16:01:07.630537329Z" }, "pages": [ { "url": "https://mailpace.com/category/changelog", "kind": "changelog", "status": 200, "checkedAt": "2026-11-07T14:13:40.841899008Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "38f92a159d1b" }, { "url": "https://mailpace.com/privacy", "kind": "privacy", "status": 200, "checkedAt": "2026-11-07T14:13:45.28058492Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "e6b0fea49c1d" }, { "url": "https://mailpace.com/terms", "kind": "terms", "status": 200, "checkedAt": "2026-11-07T14:13:45.480605157Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "24f1eed01dad" } ], "updatedAt": "2026-11-07T16:01:07.630537329Z" } }, "answer": "Mailchimp Transactional (Mandrill) scores 61.5 (C) on agent readiness against MailPace's 58.4 (C), and leads in 3 of 7 scored categories. MailPace leads on agent ergonomics and maintenance \u0026 community.", "b": { "slug": "mandrill", "name": "Mailchimp Transactional (Mandrill)", "vendor": "Intuit Mailchimp", "vendorUrl": "https://mailchimp.com/features/transactional-email/", "kind": "http-api", "category": "email", "summary": "Transactional email service from Intuit Mailchimp, formerly Mandrill. It sends application email and SMS through an HTTP API, SMTP or a hosted MCP server, with templates, inbound routing, webhooks and reporting, as a paid add-on to a Mailchimp plan.", "url": "https://www.anchorterminal.com/tools/mandrill", "markdownUrl": "https://www.anchorterminal.com/tools/mandrill.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/mandrill.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/mandrill.json", "dns": "mandrill.grade.anchorterminal.com", "repo": "https://github.com/mailchimp/mailchimp-client-lib-codegen", "license": "Proprietary service under Mailchimp's Standard Terms of Use and Additional Terms. The client libraries are under Mailchimp's own client library licence agreement", "transports": [ "http" ], "remoteUrl": "https://mandrillapp.com/api/1.4", "packages": [ { "registry": "npm", "name": "@mailchimp/mailchimp_transactional" }, { "registry": "pypi", "name": "mailchimp-transactional" } ], "auth": "api-key", "authNotes": "Self-serve API key, created in the Transactional web app at mandrillapp.com/settings by an Owner or Admin of the Mailchimp account. The key goes in the JSON body of every POST as `key`, and the MCP server takes it as `Authorization: Bearer`. A key can be limited to chosen endpoints and to IP addresses, and a restricted key needs the AI Agents permission group to use the MCP server. Test keys work only in test mode. There is no OAuth for this API.", "pricing": "paid", "pricingNotes": "$20 per block of 25,000 emails a month for 1 to 20 blocks, falling in steps to $10 at 161 blocks or more, on top of a Standard or Premium Mailchimp marketing plan. Blocks are billed monthly in advance and unused emails do not roll over. A dedicated IP is $29.95 a month. An agent's owner can start without a contract through the demo, which gives 500 emails once to the account's own verified domain on any Mailchimp account, free plan included. Test keys send nothing and cost nothing (https://mailchimp.com/pricing/transactional-email/).", "priceSummary": "$29.95 / mo", "where": "hosted", "x402": { "level": "no", "evidence": "No x402, MPP or L402 in the developer docs, the OpenAPI file or the pricing page (checked 2026-10-08).", "endpoints": [] }, "toolCount": 9, "popularity": { "githubStars": null, "npmWeekly": 226039, "pypiWeekly": 132016, "asOf": "2026-10-08" }, "docsUrl": "https://mailchimp.com/developer/transactional/docs/fundamentals/", "llmsTxt": "https://mailchimp.com/developer/transactional/llms.txt", "openapi": "https://mailchimp.com/developer/openapi/api-reference-2.json", "capabilities": [ "email.send", "email.templates", "email.inbound", "email.domains", "email.analytics" ], "tags": [ "hosted", "paid", "mcp", "openapi", "llms-txt", "api-key", "smtp", "webhooks", "inbound", "sandbox", "typescript", "python", "status-page", "soc2" ], "lastRelease": "2026-03-24", "graded": true, "anchor": { "graded": true, "score": 61.5, "grade": "C", "agentReady": false, "rank": 607, "ranked": true, "rankOf": 1486, "categoryRank": 15, "methodology": "0.7", "run": "2026-10-01", "scores": { "ergonomics": 60, "maintenance": 28, "payments": 35, "reliability": 70, "schema": 79, "security": 68, "transparency": 71 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-11-04" }, "negative": 0, "verdict": "A public OpenAPI 3.1 file covers all 99 operations, the docs serve Markdown and llms.txt, and keys can be limited by endpoint and IP address. Sending needs a Standard or Premium Mailchimp plan plus $20 blocks of 25,000 emails. No send idempotency key or SLA was found, and the newest dated release is from 24 March 2026.", "bestFor": "Teams already paying for Mailchimp Standard or Premium that want transactional mail, inbound parsing and an MCP server on the same account.", "strengths": [ "OpenAPI 3.1 file for all 99 operations, with typed error bodies for 401, 402, 404, 422, 429 and 500", "Hosted MCP server at `https://mandrillapp.com/mcp` with 9 tools, three of which list, describe and call API endpoints", "API keys can be limited to named endpoints and to IP addresses, and test keys send nothing", "Every docs page has a Markdown copy at the same URL plus `.md`, with an llms.txt index", "Status page lists Mailchimp Transactional as its own component with month-by-month event history" ], "weaknesses": [ "Full use needs a Standard or Premium Mailchimp marketing plan in addition to the email blocks", "No idempotency key on `/messages/send`, and no `Retry-After` header found in the docs or the specification", "Three delivery-delay incidents in September 2026, two of them lasting more than four hours", "The newest client library and specification release is 24 March 2026, and the changelog's newest entry is 19 August 2025", "The docs give three API version paths (1.0, 1.3 and 1.4), and the llms.txt link to the OpenAPI file returns 404" ], "agentNotes": [ "Send every call as POST with the key in the JSON body as `key`. The MCP server takes the same key as `Authorization: Bearer`", "Use a test API key while building. Test sends are free, capped at 10,000 a day, and deliver nothing", "Verify the sending domain with DKIM and DMARC first. Mail from an unverified domain is rejected with the reason `unsigned`", "Keep `/messages/search` under 20 calls a minute and set `limit` (default 100, maximum 1,000). There is no offset, so use an activity export for more", "For a restricted key that must also use the MCP server, enable the AI Agents permission group on the key" ], "metrics": { "kind": "remote", "measured": false }, "reviewCount": 0, "avgRating": 0, "history": [ { "basis": "public evidence", "confidence": "medium", "grade": "C", "methodology": "0.7", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 61.5 } ], "editorialScores": { "ergonomics": 60, "maintenance": 28, "payments": 35, "reliability": 70, "schema": 79, "security": 68, "transparency": 64 }, "provenanceScore": 78, "checked": { "categories": { "ergonomics": "2026-11-04", "maintenance": "2026-11-04", "payments": "2026-11-04", "reliability": "2026-11-04", "schema": "2026-11-04", "security": "2026-11-04", "transparency": "2026-11-04" }, "last": "2026-11-04", "lastMoved": "2026-11-04", "oldest": "2026-11-04", "stale": false, "staleAfterDays": 90 } }, "connect": { "install": "npm install @mailchimp/mailchimp_transactional", "http": "curl -sS -X POST \"https://mandrillapp.com/api/1.0/users/ping\" \\\n --header 'Content-Type: application/json' \\\n --data-raw '{ \"key\": \"YOUR_API_KEY\" }'", "claudeCode": "claude mcp add --transport http mctx-mcp https://mandrillapp.com/mcp \\\n -H \"Authorization: Bearer YOUR_API_KEY\"", "config": { "mcpServers": { "mctx-mcp": { "headers": { "Authorization": "Bearer YOUR_API_KEY" }, "type": "http", "url": "https://mandrillapp.com/mcp" } } } }, "letme": { "capability": "https://letme.dev/email.send", "tool": "https://letme.dev/mandrill" }, "sameCompany": [ "mailchimp-marketing" ], "area": "communication", "unitPrices": [ { "item": "Email block, 1 to 20 blocks", "unit": "1k-emails", "usd": 0.8, "note": "$20 per block of 25,000 emails, billed monthly, unused emails do not roll over. Needs a Standard or Premium Mailchimp plan" }, { "item": "Email block, 21 to 40 blocks", "unit": "1k-emails", "usd": 0.72, "note": "$18 per block of 25,000" }, { "item": "Email block, 41 to 80 blocks", "unit": "1k-emails", "usd": 0.64, "note": "$16 per block of 25,000" }, { "item": "Email block, 81 to 120 blocks", "unit": "1k-emails", "usd": 0.56, "note": "$14 per block of 25,000" }, { "item": "Email block, 121 to 160 blocks", "unit": "1k-emails", "usd": 0.48, "note": "$12 per block of 25,000" }, { "item": "Email block, 161 blocks or more", "unit": "1k-emails", "usd": 0.4, "note": "$10 per block of 25,000" }, { "item": "Dedicated IP", "unit": "month", "usd": 29.95 } ], "provenance": { "legalEntity": "The Rocket Science Group LLC d/b/a Mailchimp", "domain": "mailchimp.com", "domainRegistered": "2001-06-29", "endpointOnVendorDomain": false, "terms": "https://mailchimp.com/legal/terms/", "privacy": "https://www.intuit.com/privacy/statement/", "statusPage": "https://status.mailchimp.com", "changelog": "https://mailchimp.com/developer/release-notes/", "securityTxt": "valid", "checked": "2026-10-08", "notes": [ "The Standard Terms of Use, updated and effective 10 October 2025, name The Rocket Science Group LLC d/b/a Mailchimp, 405 N Angier Ave. NE, Atlanta, Georgia, part of the Intuit group with Intuit Inc. as parent.", "Transactional Email is also governed by the section For Transactional Email (formerly Mandrill) of the Additional Terms at https://mailchimp.com/legal/additional-terms/, which the Standard Terms incorporate, and by the API Use Policy updated 1 August 2023.", "The privacy field points at the Intuit Global Privacy Statement, last updated 9 March 2026. Mailchimp's terms name it as the privacy document for the service, mailchimp.com/legal/privacy redirects to it, and it names The Rocket Science Group LLC d/b/a Mailchimp. Mailchimp publishes no separate privacy policy.", "The API and the MCP server are served from mandrillapp.com, registered 2011-09-01, not from mailchimp.com (RDAP, Verisign).", "mailchimp.com/.well-known/security.txt holds one Contact line that points at the responsible disclosure section of the security page, with no Expires field. mandrillapp.com has no security.txt (404).", "The changelog covers the Marketing and Transactional APIs together. Its newest entry is dated 19 August 2025." ], "score": 78 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/mandrill.json", "live": { "slug": "mandrill", "probe": { "target": "https://mandrillapp.com/api/1.4", "method": "get", "lastAt": "2026-11-07T18:20:37.296285884Z", "lastOk": true, "lastStatus": 404, "lastMs": 483, "authRequired": false, "uptime24h": 100, "uptime30d": 100, "p50ms24h": 431, "p95ms24h": 500, "samples24h": 239, "samples30d": 7420, "days": [ { "date": "2026-10-08", "probes": 50, "ok": 50 }, { "date": "2026-10-09", "probes": 250, "ok": 250 }, { "date": "2026-10-10", "probes": 247, "ok": 247 }, { "date": "2026-10-11", "probes": 247, "ok": 247 }, { "date": "2026-10-12", "probes": 247, "ok": 247 }, { "date": "2026-10-13", "probes": 248, "ok": 248 }, { "date": "2026-10-14", "probes": 249, "ok": 249 }, { "date": "2026-10-15", "probes": 253, "ok": 253 }, { "date": "2026-10-16", "probes": 252, "ok": 252 }, { "date": "2026-10-17", "probes": 253, "ok": 253 }, { "date": "2026-10-18", "probes": 256, "ok": 256 }, { "date": "2026-10-19", "probes": 255, "ok": 255 }, { "date": "2026-10-20", "probes": 252, "ok": 252 }, { "date": "2026-10-21", "probes": 253, "ok": 253 }, { "date": "2026-10-22", "probes": 253, "ok": 253 }, { "date": "2026-10-23", "probes": 248, "ok": 248 }, { "date": "2026-10-24", "probes": 251, "ok": 251 }, { "date": "2026-10-25", "probes": 250, "ok": 250 }, { "date": "2026-10-26", "probes": 252, "ok": 252 }, { "date": "2026-10-27", "probes": 249, "ok": 249 }, { "date": "2026-10-28", "probes": 251, "ok": 251 }, { "date": "2026-10-29", "probes": 248, "ok": 248 }, { "date": "2026-10-30", "probes": 249, "ok": 249 }, { "date": "2026-10-31", "probes": 251, "ok": 251 }, { "date": "2026-11-01", "probes": 249, "ok": 249 }, { "date": "2026-11-02", "probes": 250, "ok": 250 }, { "date": "2026-11-03", "probes": 248, "ok": 248 }, { "date": "2026-11-04", "probes": 246, "ok": 246 }, { "date": "2026-11-05", "probes": 185, "ok": 185 }, { "date": "2026-11-06", "probes": 241, "ok": 241 }, { "date": "2026-11-07", "probes": 187, "ok": 187 } ] }, "vendorStatus": { "page": "https://status.mailchimp.com", "indicator": "unknown", "summary": "no machine-readable status found", "checkedAt": "2026-11-03T02:16:31.252088609Z" }, "versions": [ { "registry": "npm", "name": "@mailchimp/mailchimp_transactional", "version": "1.4.1", "seenAt": "2026-11-06T23:42:24.513614416Z" }, { "registry": "pypi", "name": "mailchimp-transactional", "version": "1.4.1", "released": "2026-03-24", "seenAt": "2026-11-06T23:42:24.765704244Z" } ], "githubStars": 48, "npmWeekly": 267560, "pypiWeekly": 149515, "securityTxt": { "url": "https://mailchimp.com/.well-known/security.txt", "state": "valid", "checkedAt": "2026-11-07T15:59:41.954623744Z" }, "llmsTxt": { "url": "https://mailchimp.com/developer/transactional/llms.txt", "ok": true, "status": 200, "checkedAt": "2026-11-07T15:32:58.112257648Z" }, "domain": { "domain": "mailchimp.com", "registered": "2001-06-29", "source": "https://rdap.verisign.com/com/v1/domain/mailchimp.com", "checkedAt": "2026-11-01T14:09:51.942989092Z" }, "pages": [ { "url": "https://mailchimp.com/pricing/transactional-email/", "kind": "pricing", "status": 200, "checkedAt": "2026-11-07T14:13:48.331406023Z", "changedAt": "2026-11-07T14:13:48.331406023Z", "fingerprint": "fe3263508aea" } ], "mcpTools": { "url": "https://mandrillapp.com/mcp", "checkedAt": "2026-11-07T01:46:08.092473858Z", "status": "error", "note": "initialize: Authorization: Bearer \u003capi_key\u003e required", "changedAt": "2026-11-07T01:46:08.092473858Z" }, "github": { "repo": "mailchimp/mailchimp-client-lib-codegen", "checkedAt": "2026-11-02T09:02:15.007153606Z", "stars": 48, "archived": false, "issuesEnabled": false, "pushedAt": "2026-07-16T14:41:25Z", "openIssues": 0, "openPRs": 13, "issuesOpened90d": 0, "issuesClosed90d": 0, "prsMerged90d": 0, "ci": { "branch": "main", "runs": 50, "success": 15, "failure": 15, "other": 20, "latest": "failure", "latestAt": "2026-07-16T14:43:21Z" } }, "updatedAt": "2026-11-07T18:20:37.296285884Z" } }, "edges": [ { "by": 37, "category": "maintenance", "leads": "mailpace", "name": "Maintenance \u0026 community", "reasons": { "a": "Email Status API documented on 22 October 2026, and the MCP server rewritten as 2.0.0 on 4 November 2026, two days before this check (30). In the 90 days from 8 August, the Q3 changelog post of 31 August, the Email Status docs of 22 October, a mailpace-rails push on 17 October and the MCP rewrite, but only one changelog post (15 of 20). A closed service with email support. Three pull requests to the MCP repository from 2025 have no reply (8 of 15). Not in the official MCP registry (search for mailpace returned nothing on 6 November). The Node library was last pushed in October 2024 and Go in January 2024, while mailpace-rails is current (7 of 15). The MCP server gained CI with tests on 4 November; the older SDKs weren't checked for CI (5 of 10). Total 65.", "b": "The newest dated Transactional release is specification 1.4.1 on 24 March 2026 (commit a996b63 in the generator repository), with the Node and Python libraries at 1.4.1, 225 days before this check (0). No dated Transactional release or changelog entry in the 90 days from 6 August. The newest Transactional release-notes entry is 19 August 2025 (0). A public changelog, a support contact and an API help address in the specification. We saw no public issue replies (6). The Node and Python libraries are both at 1.4.1 and match the current API version (15). The generator repository has workflows that validate the specification and build and test each library, and the Node library was updated in February 2024 for an Axios advisory. The test workflow needs a secret key, so we could not see results (7). 0+0+6+15+7 = 28." }, "scores": { "a": 65, "b": 28 } }, { "by": 25, "category": "schema", "leads": "mandrill", "name": "Schema \u0026 documentation", "reasons": { "a": "No OpenAPI or other machine-readable contract for the HTTPS API. The MCP server's 12 tools have typed zod inputs and output schemas, but that server isn't published yet, so partial credit (8 of 25). llms.txt answers 404 on mailpace.com and docs.mailpace.com, and no Markdown copies are served (0). The reference states what each endpoint does, and the introduction says when not to use it (transactional only, no batch, no static IPs) (12 of 20). Field tables give type, examples and required or optional, with enums for status, sort and direction and the 50-recipient cap in text (9 of 15). Examples in curl and six languages and a full table of error responses with messages, though several listed messages have a broken quote (`{\"error:\"...`) and the send reference says 30 MB where the home page says 25 MB (12 of 15). Version in the path with a promise that an old version runs until a published end-of-life date, and dated changelog posts (13 of 15). Total 54.", "b": "An OpenAPI 3.1 file with all 99 operations is public at mailchimp.com/developer/openapi/api-reference-2.json, and a Swagger 2.0 copy sits in the client library repository. The link to it in the Transactional llms.txt returns 404 (25). llms.txt for the developer site and for Transactional, and a Markdown copy of every page at the URL plus `.md` (10). Each operation has a summary and a description averaging about 120 characters. They say what a call does and seldom when not to use it (11). Request bodies carry 36 enums, required fields, date patterns and minimum and maximum values. Headers, metadata and merge variables are free-form objects (11). Reference pages show request and response samples with code in eight languages, and each operation lists typed error bodies. The OpenAPI file itself has no examples (13). The version is in the path, but the docs use 1.0, 1.3 and 1.4 in different places, and the public changelog has nothing newer than 19 August 2025, so the move to 1.4 in March 2026 is not in it (9)." }, "scores": { "a": 54, "b": 79 } }, { "by": 18, "category": "security", "leads": "mandrill", "name": "Security \u0026 auth", "reasons": { "a": "Per-domain server tokens that can only send from and read status for their domain, and an organisation token that creates, renames and revokes domain tokens through the Domains API. Tokens travel in headers only. The authentication page still tells users to contact support to regenerate a leaked token (25 of 30). No read-only token. A domain token can't touch other domains, and the unpublished MCP server has an optional recipient allowlist. No approval step on the hosted API (8 of 20). Inbound mail reaches the customer's webhook as untrusted content, and Email Status returns bounce text. The MCP README warns about prompt injection and suggests the allowlist (9 of 15). The dashboard keeps sent mail for 30 days; no log of API calls was found (6 of 15). No security.txt (404 on mailpace.com and app.mailpace.com), no disclosure policy, bug bounty, SOC 2 or ISO 27001. WebAuthn-only two-factor sign-in and Ed25519-signed webhooks are documented (2 of 20). Total 50.", "b": "API keys are created and revoked in the web app, several to an account, and each can be limited to chosen endpoints and to IP addresses. Keys do not expire and no rotation tooling was found. A new key has full account access by default. The key travels in the JSON body or a Bearer header, not the URL (26). Per-endpoint key permissions, IP limits, test keys that send nothing and subaccounts that can be paused. No approval step for sends or deletes (15). The API and the MCP server return inbound mail and stored message content, which is untrusted text. No guidance on prompt injection was found in the MCP guide or the docs (3). The Account Security page lists the IP addresses that used the account and whether each came by API, SMTP or web, and searches can filter by API key (10). A responsible disclosure programme with no rewards, a security.txt with a contact and no Expires field, SOC 2 reports and ISO 27001 per the security page, and regular penetration tests. No public advisory feed found (14)." }, "scores": { "a": 50, "b": 68 } }, { "by": 11, "category": "ergonomics", "leads": "mailpace", "name": "Agent ergonomics", "reasons": { "a": "Responses are small, the send returns an id and status and Email Status returns one email (18 of 25). Only the domains list takes `limit`, `offset`, `sort` and `direction`; there is no endpoint to list or search sent mail (8 of 20). Errors are JSON with a human message and an HTTP status for each case in the documented table, with no stable error codes (14 of 20). `Idempotency-Key` on sends, kept 24 hours per token, and failed validations are not stored so they can be retried. The MCP server marks send as not idempotent and revoke as destructive (18 of 20). A send needs from, to, a subject and a body; official libraries for Node, Rails, Go and PHP transports and an SMTP route (13 of 15). Total 71.", "b": "Graded on the API. `/messages/search` takes a `limit` up to 1,000 and send responses are one small object per recipient. No field selection was found. The hosted MCP server has 9 tools and reaches the 99 operations through `list_api`, `describe_api` and `call_api`, which keeps the definitions small (16). Search filters by date, tag, sender and API key, with no offset or cursor, so larger result sets go through a queued export (10). Errors return `status`, `code`, `name` and `message`, and the fundamentals page pairs common ones with a cause and a fix (16). No idempotency key. Test keys let an agent try sends without delivery, and scheduled messages can be listed and cancelled. The MCP tool annotations need a key to list, so they're unread (5). A send needs a key, a sender, a recipient and content. Official libraries for Node, Python, PHP and Ruby (13)." }, "scores": { "a": 71, "b": 60 } }, { "by": 10, "category": "payments", "leads": "mandrill", "name": "Payments \u0026 pricing", "reasons": { "a": "No x402, MPP or L402 (0). $10 a month for 10,000 emails and $1 per 1,000 after, loaded from Paddle on the pricing page and stated in the comparison pages' tables without login (20). A free plan of up to 100 emails a month is available only by emailing support, so it isn't self-serve (5 of 20). Signup, DKIM verification and payment happen in a browser (0). Total 25.", "b": "No x402, MPP or L402 (0). Block prices are public without a login, $20 per 25,000 emails falling to $10, and $29.95 a month for a dedicated IP. Full use also needs a Standard or Premium marketing plan, whose price is on a separate page (20). The demo gives 500 emails once on any Mailchimp account, free plan included. We take 5 off because it sends only to the account's own verified domain and we could not confirm that signup asks for no card (15). A person signs up in a browser, enables the add-on, creates a key and sets DNS records, so there is no autonomous route (0)." }, "scores": { "a": 25, "b": 35 } } ], "facts": [ { "a": "HTTP API", "b": "HTTP API", "name": "Kind" }, { "a": "OhMySMTP Ltd", "b": "Intuit Mailchimp", "name": "Vendor" }, { "a": "no (local only)", "b": "https://mandrillapp.com/api/1.4", "name": "Hosted endpoint" }, { "a": "HTTP", "b": "HTTP", "name": "Transports" }, { "a": "API key", "b": "API key", "name": "Auth" }, { "a": "Paid", "b": "Paid", "name": "Pricing" }, { "a": "no", "b": "no", "name": "x402" }, { "a": "none", "b": "Proprietary service under Mailchimp's Standard Terms of Use and Additional Terms. The client libraries are under Mailchimp's own client library licence agreement", "name": "Licence" }, { "a": "12", "b": "9", "name": "Tools exposed" }, { "a": "no", "b": "no", "name": "Read-only variant documented" }, { "a": "no", "b": "yes", "name": "llms.txt" }, { "a": "2026-10-22", "b": "2026-03-24", "name": "Last release" }, { "a": "2026-01-09", "b": "no date given", "name": "Terms last updated" }, { "a": "2026-08-30", "b": "2026-03-09", "name": "Privacy policy last updated" }, { "a": "not found in the text", "b": "yes", "name": "Customer content may train models" }, { "a": "yes", "b": "not found in the text", "name": "Terms restrict automated access" }, { "a": "not found in the text", "b": "not found in the text", "name": "Terms restrict benchmarking" }, { "a": "not found in the text", "b": "yes", "name": "Terms or service can change without notice" }, { "a": "not found in the text", "b": "yes", "name": "Arbitration or class-action waiver" }, { "a": "1 stars, 207 npm/wk", "b": "226k npm/wk, 132k PyPI/wk", "name": "Popularity" } ], "faq": [ { "answer": "Mailchimp Transactional (Mandrill) scores 61.5 (C) on agent readiness against MailPace's 58.4 (C), and leads in 3 of 7 scored categories. MailPace leads on agent ergonomics and maintenance \u0026 community.", "question": "Which is better for AI agents, MailPace or Mailchimp Transactional (Mandrill)?" }, { "answer": "Both need an API key.", "question": "Do MailPace and Mailchimp Transactional (Mandrill) need an API key?" }, { "answer": "No hosted endpoint is listed for MailPace. Mailchimp Transactional (Mandrill) has a hosted endpoint at https://mandrillapp.com/api/1.4.", "question": "Can an agent call MailPace and Mailchimp Transactional (Mandrill) without installing anything?" } ], "goodFor": [ { "aheadOn": [ "Agent ergonomics, 71 against 60", "Maintenance \u0026 community, 65 against 28" ], "also": null, "goodFor": "Low-volume transactional mail from EU-hosted infrastructure with idempotent sends and no tracking.", "slug": "mailpace", "watchFor": "No OpenAPI spec, llms.txt or Markdown docs for agents; the reference is Docusaurus pages" }, { "aheadOn": [ "Schema \u0026 documentation, 79 against 54", "Security \u0026 auth, 68 against 50", "Payments \u0026 pricing, 35 against 25" ], "also": [ "A hosted endpoint, with nothing to install" ], "goodFor": "Teams already paying for Mailchimp Standard or Premium that want transactional mail, inbound parsing and an MCP server on the same account.", "slug": "mandrill", "watchFor": "Full use needs a Standard or Premium Mailchimp marketing plan in addition to the email blocks" } ], "history": { "mailpace": null, "mandrill": [ { "causes": [ "correction" ], "date": "2026-11-04", "delta": 3.4, "from": 58.1, "fromGrade": "C", "to": 61.5, "toGrade": "C" } ] }, "job": { "capability": "email.send", "name": "Sending email" }, "others": [ { "json": "https://www.anchorterminal.com/compare/ahasend-vs-mailpace.json", "title": "AhaSend API + MCP vs MailPace", "url": "https://www.anchorterminal.com/compare/ahasend-vs-mailpace" }, { "json": "https://www.anchorterminal.com/compare/ahasend-vs-mandrill.json", "title": "AhaSend API + MCP vs Mailchimp Transactional (Mandrill)", "url": "https://www.anchorterminal.com/compare/ahasend-vs-mandrill" }, { "json": "https://www.anchorterminal.com/compare/amazon-ses-vs-mailpace.json", "title": "Amazon SES vs MailPace", "url": "https://www.anchorterminal.com/compare/amazon-ses-vs-mailpace" }, { "json": "https://www.anchorterminal.com/compare/amazon-ses-vs-mandrill.json", "title": "Amazon SES vs Mailchimp Transactional (Mandrill)", "url": "https://www.anchorterminal.com/compare/amazon-ses-vs-mandrill" }, { "json": "https://www.anchorterminal.com/compare/brevo-vs-mailpace.json", "title": "Brevo API + MCP vs MailPace", "url": "https://www.anchorterminal.com/compare/brevo-vs-mailpace" }, { "json": "https://www.anchorterminal.com/compare/brevo-vs-mandrill.json", "title": "Brevo API + MCP vs Mailchimp Transactional (Mandrill)", "url": "https://www.anchorterminal.com/compare/brevo-vs-mandrill" }, { "json": "https://www.anchorterminal.com/compare/cloudflare-email-service-vs-mailpace.json", "title": "Cloudflare Email Service vs MailPace", "url": "https://www.anchorterminal.com/compare/cloudflare-email-service-vs-mailpace" }, { "json": "https://www.anchorterminal.com/compare/cloudflare-email-service-vs-mandrill.json", "title": "Cloudflare Email Service vs Mailchimp Transactional (Mandrill)", "url": "https://www.anchorterminal.com/compare/cloudflare-email-service-vs-mandrill" }, { "json": "https://www.anchorterminal.com/compare/groundmail-vs-mailpace.json", "title": "Groundmail API + MCP vs MailPace", "url": "https://www.anchorterminal.com/compare/groundmail-vs-mailpace" }, { "json": "https://www.anchorterminal.com/compare/groundmail-vs-mandrill.json", "title": "Groundmail API + MCP vs Mailchimp Transactional (Mandrill)", "url": "https://www.anchorterminal.com/compare/groundmail-vs-mandrill" }, { "json": "https://www.anchorterminal.com/compare/loops-vs-mailpace.json", "title": "Loops API + MCP vs MailPace", "url": "https://www.anchorterminal.com/compare/loops-vs-mailpace" }, { "json": "https://www.anchorterminal.com/compare/loops-vs-mandrill.json", "title": "Loops API + MCP vs Mailchimp Transactional (Mandrill)", "url": "https://www.anchorterminal.com/compare/loops-vs-mandrill" }, { "json": "https://www.anchorterminal.com/compare/mailersend-vs-mailpace.json", "title": "MailerSend vs MailPace", "url": "https://www.anchorterminal.com/compare/mailersend-vs-mailpace" }, { "json": "https://www.anchorterminal.com/compare/mailersend-vs-mandrill.json", "title": "MailerSend vs Mailchimp Transactional (Mandrill)", "url": "https://www.anchorterminal.com/compare/mailersend-vs-mandrill" }, { "json": "https://www.anchorterminal.com/compare/mailgun-vs-mailpace.json", "title": "Mailgun API + MCP vs MailPace", "url": "https://www.anchorterminal.com/compare/mailgun-vs-mailpace" }, { "json": "https://www.anchorterminal.com/compare/mailgun-vs-mandrill.json", "title": "Mailgun API + MCP vs Mailchimp Transactional (Mandrill)", "url": "https://www.anchorterminal.com/compare/mailgun-vs-mandrill" }, { "json": "https://www.anchorterminal.com/compare/mailjet-vs-mailpace.json", "title": "Mailjet API + MCP vs MailPace", "url": "https://www.anchorterminal.com/compare/mailjet-vs-mailpace" }, { "json": "https://www.anchorterminal.com/compare/mailjet-vs-mandrill.json", "title": "Mailjet API + MCP vs Mailchimp Transactional (Mandrill)", "url": "https://www.anchorterminal.com/compare/mailjet-vs-mandrill" }, { "json": "https://www.anchorterminal.com/compare/mailpace-vs-mailtrap.json", "title": "MailPace vs Mailtrap Email API + MCP", "url": "https://www.anchorterminal.com/compare/mailpace-vs-mailtrap" }, { "json": "https://www.anchorterminal.com/compare/mailpace-vs-postmark.json", "title": "MailPace vs Postmark API + MCP", "url": "https://www.anchorterminal.com/compare/mailpace-vs-postmark" }, { "json": "https://www.anchorterminal.com/compare/mailpace-vs-resend.json", "title": "MailPace vs Resend API + MCP", "url": "https://www.anchorterminal.com/compare/mailpace-vs-resend" }, { "json": "https://www.anchorterminal.com/compare/mailpace-vs-sendgrid.json", "title": "MailPace vs Twilio SendGrid", "url": "https://www.anchorterminal.com/compare/mailpace-vs-sendgrid" }, { "json": "https://www.anchorterminal.com/compare/mailpace-vs-sendlayer.json", "title": "MailPace vs SendLayer", "url": "https://www.anchorterminal.com/compare/mailpace-vs-sendlayer" }, { "json": "https://www.anchorterminal.com/compare/mailpace-vs-smtp2go.json", "title": "MailPace vs SMTP2GO API + MCP", "url": "https://www.anchorterminal.com/compare/mailpace-vs-smtp2go" }, { "json": "https://www.anchorterminal.com/compare/mailpace-vs-zoho-zeptomail.json", "title": "MailPace vs Zoho CPaaS (formerly ZeptoMail)", "url": "https://www.anchorterminal.com/compare/mailpace-vs-zoho-zeptomail" }, { "json": "https://www.anchorterminal.com/compare/mailtrap-vs-mandrill.json", "title": "Mailtrap Email API + MCP vs Mailchimp Transactional (Mandrill)", "url": "https://www.anchorterminal.com/compare/mailtrap-vs-mandrill" }, { "json": "https://www.anchorterminal.com/compare/mandrill-vs-postmark.json", "title": "Mailchimp Transactional (Mandrill) vs Postmark API + MCP", "url": "https://www.anchorterminal.com/compare/mandrill-vs-postmark" }, { "json": "https://www.anchorterminal.com/compare/mandrill-vs-resend.json", "title": "Mailchimp Transactional (Mandrill) vs Resend API + MCP", "url": "https://www.anchorterminal.com/compare/mandrill-vs-resend" }, { "json": "https://www.anchorterminal.com/compare/mandrill-vs-sendgrid.json", "title": "Mailchimp Transactional (Mandrill) vs Twilio SendGrid", "url": "https://www.anchorterminal.com/compare/mandrill-vs-sendgrid" }, { "json": "https://www.anchorterminal.com/compare/mandrill-vs-sendlayer.json", "title": "Mailchimp Transactional (Mandrill) vs SendLayer", "url": "https://www.anchorterminal.com/compare/mandrill-vs-sendlayer" }, { "json": "https://www.anchorterminal.com/compare/mandrill-vs-smtp2go.json", "title": "Mailchimp Transactional (Mandrill) vs SMTP2GO API + MCP", "url": "https://www.anchorterminal.com/compare/mandrill-vs-smtp2go" }, { "json": "https://www.anchorterminal.com/compare/mandrill-vs-zoho-zeptomail.json", "title": "Mailchimp Transactional (Mandrill) vs Zoho CPaaS (formerly ZeptoMail)", "url": "https://www.anchorterminal.com/compare/mandrill-vs-zoho-zeptomail" } ], "panel": null, "scores": [ { "by": 0, "edge": "", "key": "reliability", "mailpace": 70, "mandrill": 70, "name": "Reliability", "weight": 16 }, { "key": "performance", "name": "Performance", "pending": true, "weight": 10 }, { "by": 25, "edge": "mandrill", "key": "schema", "mailpace": 54, "mandrill": 79, "name": "Schema \u0026 documentation", "weight": 13 }, { "by": 11, "edge": "mailpace", "key": "ergonomics", "mailpace": 71, "mandrill": 60, "name": "Agent ergonomics", "weight": 13 }, { "by": 18, "edge": "mandrill", "key": "security", "mailpace": 50, "mandrill": 68, "name": "Security \u0026 auth", "weight": 14 }, { "by": 10, "edge": "mandrill", "key": "payments", "mailpace": 25, "mandrill": 35, "name": "Payments \u0026 pricing", "weight": 10 }, { "key": "tasks", "name": "Task success", "pending": true, "weight": 10 }, { "by": 37, "edge": "mailpace", "key": "maintenance", "mailpace": 65, "mandrill": 28, "name": "Maintenance \u0026 community", "weight": 7 }, { "by": 4, "edge": "mailpace", "key": "transparency", "mailpace": 75, "mandrill": 71, "name": "Transparency \u0026 trust", "weight": 7 } ], "summary": "Mailchimp Transactional (Mandrill) scores 61.5 (C) on agent readiness against MailPace's 58.4 (C), and leads in 3 of 7 scored categories. MailPace leads on agent ergonomics and maintenance \u0026 community. Both do sending email.", "tasks": null, "tutorials": [], "verdicts": { "mailpace": "A small transactional sender with idempotent sends, signed webhooks, a 99% availability promise in its terms and a public Upptime status record. There is no OpenAPI spec, no published rate limit, no llms.txt, and its MCP server was rewritten on 4 November 2026 but isn't on npm or in the MCP registry yet.", "mandrill": "A public OpenAPI 3.1 file covers all 99 operations, the docs serve Markdown and llms.txt, and keys can be limited by endpoint and IP address. Sending needs a Standard or Premium Mailchimp plan plus $20 blocks of 25,000 emails. No send idempotency key or SLA was found, and the newest dated release is from 24 March 2026." } }, "kind": "anchor.page", "links": { "api": "https://www.anchorterminal.com/api/v1/index.json", "html": "https://www.anchorterminal.com/compare/mailpace-vs-mandrill", "json": "https://www.anchorterminal.com/compare/mailpace-vs-mandrill.json", "llms": "https://www.anchorterminal.com/llms.txt", "markdown": "https://www.anchorterminal.com/compare/mailpace-vs-mandrill.md", "mcp": "https://www.anchorterminal.com/mcp", "slim": "https://www.anchorterminal.com/compare/mailpace-vs-mandrill.min.md" }, "markdown": "Mailchimp Transactional (Mandrill) scores 61.5 (C) on agent readiness against MailPace's 58.4 (C), and leads in 3 of 7 scored categories. MailPace leads on agent ergonomics and maintenance \u0026 community. Both do sending email.\n\n- MailPace: grade C, 58.4/100, rank #750 of 1486. Markdown https://www.anchorterminal.com/tools/mailpace.md · JSON https://www.anchorterminal.com/api/v1/tools/mailpace.json\n- Mailchimp Transactional (Mandrill): grade C, 61.5/100, rank #607 of 1486. Markdown https://www.anchorterminal.com/tools/mandrill.md · JSON https://www.anchorterminal.com/api/v1/tools/mandrill.json\n- Best email delivery APIs for AI agents: https://www.anchorterminal.com/best/email/index.md\n- All 174 email comparisons: https://www.anchorterminal.com/compare/email/index.md\n\n## Which one, for what\n\n### MailPace (C)\n\nGood for: Low-volume transactional mail from EU-hosted infrastructure with idempotent sends and no tracking.\n\nAhead on:\n- Agent ergonomics, 71 against 60\n- Maintenance \u0026 community, 65 against 28\n\nWatch for: No OpenAPI spec, llms.txt or Markdown docs for agents; the reference is Docusaurus pages\n\n### Mailchimp Transactional (Mandrill) (C)\n\nGood for: Teams already paying for Mailchimp Standard or Premium that want transactional mail, inbound parsing and an MCP server on the same account.\n\nAhead on:\n- Schema \u0026 documentation, 79 against 54\n- Security \u0026 auth, 68 against 50\n- Payments \u0026 pricing, 35 against 25\n\nAlso in its favour:\n- A hosted endpoint, with nothing to install\n\nWatch for: Full use needs a Standard or Premium Mailchimp marketing plan in addition to the email blocks\n\n\n## Why the edge\n\n### Maintenance \u0026 community: MailPace +37\n\n- MailPace (65): Email Status API documented on 22 October 2026, and the MCP server rewritten as 2.0.0 on 4 November 2026, two days before this check (30). In the 90 days from 8 August, the Q3 changelog post of 31 August, the Email Status docs of 22 October, a mailpace-rails push on 17 October and the MCP rewrite, but only one changelog post (15 of 20). A closed service with email support. Three pull requests to the MCP repository from 2025 have no reply (8 of 15). Not in the official MCP registry (search for mailpace returned nothing on 6 November). The Node library was last pushed in October 2024 and Go in January 2024, while mailpace-rails is current (7 of 15). The MCP server gained CI with tests on 4 November; the older SDKs weren't checked for CI (5 of 10). Total 65.\n- Mailchimp Transactional (Mandrill) (28): The newest dated Transactional release is specification 1.4.1 on 24 March 2026 (commit a996b63 in the generator repository), with the Node and Python libraries at 1.4.1, 225 days before this check (0). No dated Transactional release or changelog entry in the 90 days from 6 August. The newest Transactional release-notes entry is 19 August 2025 (0). A public changelog, a support contact and an API help address in the specification. We saw no public issue replies (6). The Node and Python libraries are both at 1.4.1 and match the current API version (15). The generator repository has workflows that validate the specification and build and test each library, and the Node library was updated in February 2024 for an Axios advisory. The test workflow needs a secret key, so we could not see results (7). 0+0+6+15+7 = 28.\n\n### Schema \u0026 documentation: Mailchimp Transactional (Mandrill) +25\n\n- MailPace (54): No OpenAPI or other machine-readable contract for the HTTPS API. The MCP server's 12 tools have typed zod inputs and output schemas, but that server isn't published yet, so partial credit (8 of 25). llms.txt answers 404 on mailpace.com and docs.mailpace.com, and no Markdown copies are served (0). The reference states what each endpoint does, and the introduction says when not to use it (transactional only, no batch, no static IPs) (12 of 20). Field tables give type, examples and required or optional, with enums for status, sort and direction and the 50-recipient cap in text (9 of 15). Examples in curl and six languages and a full table of error responses with messages, though several listed messages have a broken quote (`{\"error:\"...`) and the send reference says 30 MB where the home page says 25 MB (12 of 15). Version in the path with a promise that an old version runs until a published end-of-life date, and dated changelog posts (13 of 15). Total 54.\n- Mailchimp Transactional (Mandrill) (79): An OpenAPI 3.1 file with all 99 operations is public at mailchimp.com/developer/openapi/api-reference-2.json, and a Swagger 2.0 copy sits in the client library repository. The link to it in the Transactional llms.txt returns 404 (25). llms.txt for the developer site and for Transactional, and a Markdown copy of every page at the URL plus `.md` (10). Each operation has a summary and a description averaging about 120 characters. They say what a call does and seldom when not to use it (11). Request bodies carry 36 enums, required fields, date patterns and minimum and maximum values. Headers, metadata and merge variables are free-form objects (11). Reference pages show request and response samples with code in eight languages, and each operation lists typed error bodies. The OpenAPI file itself has no examples (13). The version is in the path, but the docs use 1.0, 1.3 and 1.4 in different places, and the public changelog has nothing newer than 19 August 2025, so the move to 1.4 in March 2026 is not in it (9).\n\n### Security \u0026 auth: Mailchimp Transactional (Mandrill) +18\n\n- MailPace (50): Per-domain server tokens that can only send from and read status for their domain, and an organisation token that creates, renames and revokes domain tokens through the Domains API. Tokens travel in headers only. The authentication page still tells users to contact support to regenerate a leaked token (25 of 30). No read-only token. A domain token can't touch other domains, and the unpublished MCP server has an optional recipient allowlist. No approval step on the hosted API (8 of 20). Inbound mail reaches the customer's webhook as untrusted content, and Email Status returns bounce text. The MCP README warns about prompt injection and suggests the allowlist (9 of 15). The dashboard keeps sent mail for 30 days; no log of API calls was found (6 of 15). No security.txt (404 on mailpace.com and app.mailpace.com), no disclosure policy, bug bounty, SOC 2 or ISO 27001. WebAuthn-only two-factor sign-in and Ed25519-signed webhooks are documented (2 of 20). Total 50.\n- Mailchimp Transactional (Mandrill) (68): API keys are created and revoked in the web app, several to an account, and each can be limited to chosen endpoints and to IP addresses. Keys do not expire and no rotation tooling was found. A new key has full account access by default. The key travels in the JSON body or a Bearer header, not the URL (26). Per-endpoint key permissions, IP limits, test keys that send nothing and subaccounts that can be paused. No approval step for sends or deletes (15). The API and the MCP server return inbound mail and stored message content, which is untrusted text. No guidance on prompt injection was found in the MCP guide or the docs (3). The Account Security page lists the IP addresses that used the account and whether each came by API, SMTP or web, and searches can filter by API key (10). A responsible disclosure programme with no rewards, a security.txt with a contact and no Expires field, SOC 2 reports and ISO 27001 per the security page, and regular penetration tests. No public advisory feed found (14).\n\n### Agent ergonomics: MailPace +11\n\n- MailPace (71): Responses are small, the send returns an id and status and Email Status returns one email (18 of 25). Only the domains list takes `limit`, `offset`, `sort` and `direction`; there is no endpoint to list or search sent mail (8 of 20). Errors are JSON with a human message and an HTTP status for each case in the documented table, with no stable error codes (14 of 20). `Idempotency-Key` on sends, kept 24 hours per token, and failed validations are not stored so they can be retried. The MCP server marks send as not idempotent and revoke as destructive (18 of 20). A send needs from, to, a subject and a body; official libraries for Node, Rails, Go and PHP transports and an SMTP route (13 of 15). Total 71.\n- Mailchimp Transactional (Mandrill) (60): Graded on the API. `/messages/search` takes a `limit` up to 1,000 and send responses are one small object per recipient. No field selection was found. The hosted MCP server has 9 tools and reaches the 99 operations through `list_api`, `describe_api` and `call_api`, which keeps the definitions small (16). Search filters by date, tag, sender and API key, with no offset or cursor, so larger result sets go through a queued export (10). Errors return `status`, `code`, `name` and `message`, and the fundamentals page pairs common ones with a cause and a fix (16). No idempotency key. Test keys let an agent try sends without delivery, and scheduled messages can be listed and cancelled. The MCP tool annotations need a key to list, so they're unread (5). A send needs a key, a sender, a recipient and content. Official libraries for Node, Python, PHP and Ruby (13).\n\n### Payments \u0026 pricing: Mailchimp Transactional (Mandrill) +10\n\n- MailPace (25): No x402, MPP or L402 (0). $10 a month for 10,000 emails and $1 per 1,000 after, loaded from Paddle on the pricing page and stated in the comparison pages' tables without login (20). A free plan of up to 100 emails a month is available only by emailing support, so it isn't self-serve (5 of 20). Signup, DKIM verification and payment happen in a browser (0). Total 25.\n- Mailchimp Transactional (Mandrill) (35): No x402, MPP or L402 (0). Block prices are public without a login, $20 per 25,000 emails falling to $10, and $29.95 a month for a dedicated IP. Full use also needs a Standard or Premium marketing plan, whose price is on a separate page (20). The demo gives 500 emails once on any Mailchimp account, free plan included. We take 5 off because it sends only to the account's own verified domain and we could not confirm that signup asks for no card (15). A person signs up in a browser, enables the add-on, creates a key and sets DNS records, so there is no autonomous route (0).\n\n## Score by category\n\n| Category | Weight | MailPace | Mailchimp Transactional (Mandrill) | Edge |\n| --- | --- | --- | --- | --- |\n| Reliability | 16% (20 this run) | 70 | 70 | even |\n| Performance | 10%, pending | pending | pending | not scored in this run |\n| Schema \u0026 documentation | 13% (16.2 this run) | 54 | 79 | Mailchimp Transactional (Mandrill) +25 |\n| Agent ergonomics | 13% (16.2 this run) | 71 | 60 | MailPace +11 |\n| Security \u0026 auth | 14% (17.5 this run) | 50 | 68 | Mailchimp Transactional (Mandrill) +18 |\n| Payments \u0026 pricing | 10% (12.5 this run) | 25 | 35 | Mailchimp Transactional (Mandrill) +10 |\n| Task success | 10%, pending | pending | pending | not scored in this run |\n| Maintenance \u0026 community | 7% (8.8 this run) | 65 | 28 | MailPace +37 |\n| Transparency \u0026 trust | 7% (8.8 this run) | 75 | 71 | MailPace +4 |\n| Negative events | ≤15 | 0 | 0 | |\n| **Total** | | **58.4 · C** | **61.5 · C** | |\n\n## Facts side by side\n\n| Fact | MailPace | Mailchimp Transactional (Mandrill) |\n| --- | --- | --- |\n| Kind | HTTP API | HTTP API |\n| Vendor | OhMySMTP Ltd | Intuit Mailchimp |\n| Hosted endpoint | no (local only) | `https://mandrillapp.com/api/1.4` |\n| Transports | HTTP | HTTP |\n| Auth | API key | API key |\n| Pricing | Paid | Paid |\n| x402 | no | no |\n| Licence | none | Proprietary service under Mailchimp's Standard Terms of Use and Additional Terms. The client libraries are under Mailchimp's own client library licence agreement |\n| Tools exposed | 12 | 9 |\n| Read-only variant documented | no | no |\n| llms.txt | no | yes |\n| Last release | 2026-10-22 | 2026-03-24 |\n| Terms last updated | 2026-01-09 | no date given |\n| Privacy policy last updated | 2026-08-30 | 2026-03-09 |\n| Customer content may train models | not found in the text | yes |\n| Terms restrict automated access | yes | not found in the text |\n| Terms restrict benchmarking | not found in the text | not found in the text |\n| Terms or service can change without notice | not found in the text | yes |\n| Arbitration or class-action waiver | not found in the text | yes |\n| Popularity | 1 stars, 207 npm/wk | 226k npm/wk, 132k PyPI/wk |\n\n## How the scores have moved\n\n### MailPace\n\nNo score change since it was listed.\n\n### Mailchimp Transactional (Mandrill)\n\n- +3.4 on 4 November 2026: correction\n\n## Verdicts\n\n**MailPace.** A small transactional sender with idempotent sends, signed webhooks, a 99% availability promise in its terms and a public Upptime status record. There is no OpenAPI spec, no published rate limit, no llms.txt, and its MCP server was rewritten on 4 November 2026 but isn't on npm or in the MCP registry yet.\n\n**Mailchimp Transactional (Mandrill).** A public OpenAPI 3.1 file covers all 99 operations, the docs serve Markdown and llms.txt, and keys can be limited by endpoint and IP address. Sending needs a Standard or Premium Mailchimp plan plus $20 blocks of 25,000 emails. No send idempotency key or SLA was found, and the newest dated release is from 24 March 2026.\n\n## Before you call either\n\n### MailPace\n\n1. Send a UUID in `Idempotency-Key` on every `POST /api/v1/send`, and reuse it on a retry; keys last 24 hours and are tied to one token\n2. Use the server token of the sending domain, since the From domain must match the token's domain or the API returns 403\n3. On 429 `You are sending emails too quickly` back off; no Retry-After is documented\n4. Send only transactional mail; marketing and bulk newsletters are prohibited by the docs and terms\n5. Read delivery with `GET /api/v1/domains/:domain_id/emails/:id` using the id the send returned\n\n### Mailchimp Transactional (Mandrill)\n\n1. Send every call as POST with the key in the JSON body as `key`. The MCP server takes the same key as `Authorization: Bearer`\n2. Use a test API key while building. Test sends are free, capped at 10,000 a day, and deliver nothing\n3. Verify the sending domain with DKIM and DMARC first. Mail from an unverified domain is rejected with the reason `unsigned`\n4. Keep `/messages/search` under 20 calls a minute and set `limit` (default 100, maximum 1,000). There is no offset, so use an activity export for more\n5. For a restricted key that must also use the MCP server, enable the AI Agents permission group on the key\n\n## Questions\n\n### Which is better for AI agents, MailPace or Mailchimp Transactional (Mandrill)?\n\nMailchimp Transactional (Mandrill) scores 61.5 (C) on agent readiness against MailPace's 58.4 (C), and leads in 3 of 7 scored categories. MailPace leads on agent ergonomics and maintenance \u0026 community.\n\n### Do MailPace and Mailchimp Transactional (Mandrill) need an API key?\n\nBoth need an API key.\n\n### Can an agent call MailPace and Mailchimp Transactional (Mandrill) without installing anything?\n\nNo hosted endpoint is listed for MailPace. Mailchimp Transactional (Mandrill) has a hosted endpoint at https://mandrillapp.com/api/1.4.\n\n\n## For agents\n\n- This comparison as JSON: https://www.anchorterminal.com/compare/mailpace-vs-mandrill.json, and with the fewest tokens: https://www.anchorterminal.com/compare/mailpace-vs-mandrill.min.md\n- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {\"a\": \"mailpace\", \"b\": \"mandrill\"}`. From a terminal: `anchor compare mailpace mandrill`\n- Each listing in full: https://www.anchorterminal.com/api/v1/tools/mailpace.json and https://www.anchorterminal.com/api/v1/tools/mandrill.json\n\n## Other comparisons with MailPace or Mailchimp Transactional (Mandrill)\n\n- [AhaSend API + MCP vs MailPace](https://www.anchorterminal.com/compare/ahasend-vs-mailpace.md)\n- [AhaSend API + MCP vs Mailchimp Transactional (Mandrill)](https://www.anchorterminal.com/compare/ahasend-vs-mandrill.md)\n- [Amazon SES vs MailPace](https://www.anchorterminal.com/compare/amazon-ses-vs-mailpace.md)\n- [Amazon SES vs Mailchimp Transactional (Mandrill)](https://www.anchorterminal.com/compare/amazon-ses-vs-mandrill.md)\n- [Brevo API + MCP vs MailPace](https://www.anchorterminal.com/compare/brevo-vs-mailpace.md)\n- [Brevo API + MCP vs Mailchimp Transactional (Mandrill)](https://www.anchorterminal.com/compare/brevo-vs-mandrill.md)\n- [Cloudflare Email Service vs MailPace](https://www.anchorterminal.com/compare/cloudflare-email-service-vs-mailpace.md)\n- [Cloudflare Email Service vs Mailchimp Transactional (Mandrill)](https://www.anchorterminal.com/compare/cloudflare-email-service-vs-mandrill.md)\n- [Groundmail API + MCP vs MailPace](https://www.anchorterminal.com/compare/groundmail-vs-mailpace.md)\n- [Groundmail API + MCP vs Mailchimp Transactional (Mandrill)](https://www.anchorterminal.com/compare/groundmail-vs-mandrill.md)\n- [Loops API + MCP vs MailPace](https://www.anchorterminal.com/compare/loops-vs-mailpace.md)\n- [Loops API + MCP vs Mailchimp Transactional (Mandrill)](https://www.anchorterminal.com/compare/loops-vs-mandrill.md)\n- [MailerSend vs MailPace](https://www.anchorterminal.com/compare/mailersend-vs-mailpace.md)\n- [MailerSend vs Mailchimp Transactional (Mandrill)](https://www.anchorterminal.com/compare/mailersend-vs-mandrill.md)\n- [Mailgun API + MCP vs MailPace](https://www.anchorterminal.com/compare/mailgun-vs-mailpace.md)\n- [Mailgun API + MCP vs Mailchimp Transactional (Mandrill)](https://www.anchorterminal.com/compare/mailgun-vs-mandrill.md)\n- [Mailjet API + MCP vs MailPace](https://www.anchorterminal.com/compare/mailjet-vs-mailpace.md)\n- [Mailjet API + MCP vs Mailchimp Transactional (Mandrill)](https://www.anchorterminal.com/compare/mailjet-vs-mandrill.md)\n- [MailPace vs Mailtrap Email API + MCP](https://www.anchorterminal.com/compare/mailpace-vs-mailtrap.md)\n- [MailPace vs Postmark API + MCP](https://www.anchorterminal.com/compare/mailpace-vs-postmark.md)\n- [MailPace vs Resend API + MCP](https://www.anchorterminal.com/compare/mailpace-vs-resend.md)\n- [MailPace vs Twilio SendGrid](https://www.anchorterminal.com/compare/mailpace-vs-sendgrid.md)\n- [MailPace vs SendLayer](https://www.anchorterminal.com/compare/mailpace-vs-sendlayer.md)\n- [MailPace vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/mailpace-vs-smtp2go.md)\n- [MailPace vs Zoho CPaaS (formerly ZeptoMail)](https://www.anchorterminal.com/compare/mailpace-vs-zoho-zeptomail.md)\n- [Mailtrap Email API + MCP vs Mailchimp Transactional (Mandrill)](https://www.anchorterminal.com/compare/mailtrap-vs-mandrill.md)\n- [Mailchimp Transactional (Mandrill) vs Postmark API + MCP](https://www.anchorterminal.com/compare/mandrill-vs-postmark.md)\n- [Mailchimp Transactional (Mandrill) vs Resend API + MCP](https://www.anchorterminal.com/compare/mandrill-vs-resend.md)\n- [Mailchimp Transactional (Mandrill) vs Twilio SendGrid](https://www.anchorterminal.com/compare/mandrill-vs-sendgrid.md)\n- [Mailchimp Transactional (Mandrill) vs SendLayer](https://www.anchorterminal.com/compare/mandrill-vs-sendlayer.md)\n- [Mailchimp Transactional (Mandrill) vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/mandrill-vs-smtp2go.md)\n- [Mailchimp Transactional (Mandrill) vs Zoho CPaaS (formerly ZeptoMail)](https://www.anchorterminal.com/compare/mandrill-vs-zoho-zeptomail.md)\n", "meta": { "attribution": "Anchor Terminal (https://www.anchorterminal.com)", "attributionRequired": true, "credit": "CC BY 4.0, credit Anchor Terminal and link the page or API address you took it from (https://www.anchorterminal.com/terms/#data)", "docs": "https://www.anchorterminal.com/docs/", "generatedAt": "2026-11-07", "license": "CC-BY-4.0", "method": "https://www.anchorterminal.com/benchmark/", "methodology": "0.7", "openapi": "https://www.anchorterminal.com/openapi.json", "preview": false, "run": "2026-10-01", "runLabel": "October 2026 research run", "terms": "https://www.anchorterminal.com/terms/#data" }, "page": { "breadcrumbs": [ { "name": "Home", "url": "https://www.anchorterminal.com/" }, { "name": "Compare", "url": "https://www.anchorterminal.com/compare/" }, { "name": "MailPace vs Mailchimp Transactional (Mandrill)", "url": "" } ], "description": "Mailchimp Transactional scores 61.5 (C) to MailPace's 58.4 (C) for sending email. 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