{ "data": { "a": { "slug": "postmark", "name": "Postmark API + MCP", "vendor": "Postmark (ActiveCampaign)", "vendorUrl": "https://postmarkapp.com", "kind": "http-api", "category": "email", "summary": "Transactional email API with separate broadcast streams, templates, inbound parsing and bounce handling.", "url": "https://www.anchorterminal.com/tools/postmark", "markdownUrl": "https://www.anchorterminal.com/tools/postmark.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/postmark.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/postmark.json", "repo": "https://github.com/ActiveCampaign/postmark-mcp", "license": "MIT", "transports": [ "http", "stdio" ], "remoteUrl": "https://api.postmarkapp.com", "packages": [ { "registry": "npm", "name": "postmark" }, { "registry": "npm", "name": "@activecampaign/postmark-mcp" } ], "auth": "api-key", "authNotes": "Server API token in the `X-Postmark-Server-Token` header for sending and per-server calls, and a separate `X-Postmark-Account-Token` for account-level calls. The token `POSTMARK_API_TEST` accepts requests without sending. The MCP server reads the server token from `POSTMARK_SERVER_TOKEN`.", "pricing": "freemium", "pricingNotes": "Free Developer plan with 100 emails a month, no overages and no expiry. At 10,000 emails a month Basic is $15, Pro $16.50 and Platform $18, with overage $1.80, $1.30 and $1.20 per 1,000. Pro at 125,000 is $126.50 and at 1,500,000 is $852.50. Sent and received emails both count. Dedicated IPs $50 a month from 300,000 emails a month, DMARC monitoring $14 a month per domain (https://postmarkapp.com/pricing).", "priceSummary": "$15 / mo", "where": "both", "x402": { "level": "no", "evidence": "No x402 support in docs, pricing or MCP README (checked 2026-09-30).", "endpoints": [] }, "toolCount": 24, "popularity": { "githubStars": 57, "npmWeekly": 1281479, "pypiWeekly": null, "asOf": "2026-09-30" }, "docsUrl": "https://postmarkapp.com/developer", "llmsTxt": "https://postmarkapp.com/llms.txt", "capabilities": [ "email.send", "email.inbound", "email.templates", "email.domains", "email.analytics", "email.marketing" ], "tags": [ "hosted", "freemium", "no-card", "mcp", "llms-txt", "typescript", "webhooks" ], "lastRelease": "2026-08-12", "graded": true, "anchor": { "graded": true, "score": 66.7, "grade": "B", "agentReady": false, "rank": 158, "ranked": true, "rankOf": 452, "categoryRank": 3, "methodology": "0.3", "run": "2026-10-01", "scores": { "ergonomics": 79, "maintenance": 65, "payments": 40, "reliability": 60, "schema": 81, "security": 63, "transparency": 80 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-10-01" }, "negative": 0, "verdict": "24 MCP tools, all with readOnlyHint, destructiveHint and idempotentHint, and descriptions that point to alternatives. No OpenAPI spec and no published request-rate limit.", "strengths": [ "24 MCP tools, all with readOnlyHint, destructiveHint and idempotentHint, and descriptions that point to alternatives", "Prompt-injection guidance and a webhook URL allowlist in the MCP README", "45-day retention by default, two named subprocessors and a DPA in the terms", "Per-1,000 overage rates published for every plan", "IP allowlisting for API sending since 27 August 2026" ], "weaknesses": [ "No OpenAPI spec and no published request-rate limit", "Manual account approval before sending outside your own domains", "No SOC 2, ISO 27001, disclosure policy or security.txt found for Postmark itself", "Webhooks aren't HMAC-signed", "The MCP server runs locally only and its repository has no CI" ], "agentNotes": [ "Install @activecampaign/postmark-mcp, never the unscoped postmark-mcp package", "Use the token `POSTMARK_API_TEST` to check a payload without sending", "Set `MessageStream` to `outbound` for transactional mail and a broadcast stream for bulk", "Set `WEBHOOK_URL_ALLOWLIST` so a misled createWebhook call can't send events to someone else's server", "Keep `count + offset` under 10,000 on message and bounce searches" ], "metrics": { "kind": "remote", "measured": false }, "reviewCount": 2, "avgRating": 3, "history": [ { "basis": "public evidence", "confidence": "medium", "grade": "B", "methodology": "0.3", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 66.7 } ], "editorialScores": { "ergonomics": 79, "maintenance": 65, "payments": 40, "reliability": 60, "schema": 81, "security": 63, "transparency": 69 }, "provenanceScore": 90 }, "connect": { "http": "curl https://api.postmarkapp.com/email -H \"Accept: application/json\" \\\n -H \"Content-Type: application/json\" -H \"X-Postmark-Server-Token: $POSTMARK_SERVER_TOKEN\" \\\n -d '{\"From\":\"sender@example.com\",\"To\":\"receiver@example.com\",\"Subject\":\"Hello\",\"TextBody\":\"Hello\",\"MessageStream\":\"outbound\"}'", "config": { "mcpServers": { "postmark": { "args": [ "-y", "@activecampaign/postmark-mcp" ], "command": "npx", "env": { "DEFAULT_MESSAGE_STREAM": "outbound", "DEFAULT_SENDER_EMAIL": "${DEFAULT_SENDER_EMAIL}", "POSTMARK_SERVER_TOKEN": "${POSTMARK_SERVER_TOKEN}" } } } } }, "letme": { "capability": "https://letme.dev/email.send", "tool": "https://letme.dev/postmark" }, "area": "communication", "unitPrices": [ { "item": "Basic 10k", "unit": "month", "usd": 15, "note": "10,000 emails" }, { "item": "Pro 10k", "unit": "month", "usd": 16.5, "note": "10,000 emails" }, { "item": "Platform 10k", "unit": "month", "usd": 18, "note": "10,000 emails" }, { "item": "Pro 125k", "unit": "month", "usd": 126.5, "note": "125,000 emails" }, { "item": "Overage on Basic", "unit": "1k-emails", "usd": 1.8 }, { "item": "Overage on Pro", "unit": "1k-emails", "usd": 1.3 }, { "item": "Overage on Platform", "unit": "1k-emails", "usd": 1.2 }, { "item": "Dedicated IP", "unit": "month", "usd": 50, "note": "per IP, from 300,000 emails a month" } ], "provenance": { "legalEntity": "AC PM, LLC", "domain": "postmarkapp.com", "domainRegistered": "2009-05-25", "endpointOnVendorDomain": true, "terms": "https://postmarkapp.com/terms-of-service", "privacy": "https://www.activecampaign.com/legal/privacy-policy", "statusPage": "https://status.postmarkapp.com", "changelog": "https://postmarkapp.com/updates", "securityTxt": "none", "checked": "2026-09-30", "notes": [ "AC PM, LLC is ActiveCampaign's Postmark entity. postmarkapp.com/privacy-policy redirects to ActiveCampaign's privacy policy." ], "score": 90 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/postmark.json", "live": { "slug": "postmark", "probe": { "target": "https://api.postmarkapp.com", "method": "get", "lastAt": "2026-10-05T00:57:26.416087567Z", "lastOk": true, "lastStatus": 200, "lastMs": 650, "authRequired": false, "uptime24h": 97.43, "uptime30d": 99.37, "p50ms24h": 591, "p95ms24h": 4196, "samples24h": 272, "samples30d": 1113, "days": [ { "date": "2026-09-30", "probes": 35, "ok": 35 }, { "date": "2026-10-01", "probes": 276, "ok": 276 }, { "date": "2026-10-02", "probes": 248, "ok": 248 }, { "date": "2026-10-03", "probes": 271, "ok": 271 }, { "date": "2026-10-04", "probes": 272, "ok": 265 }, { "date": "2026-10-05", "probes": 11, "ok": 11 } ] }, "vendorStatus": { "page": "https://status.postmarkapp.com", "indicator": "unknown", "summary": "no machine-readable status found", "checkedAt": "2026-10-04T21:40:24.509628112Z" }, "versions": [ { "registry": "github", "name": "ActiveCampaign/postmark-mcp", "version": "v2.1.1", "released": "2026-07-13", "seenAt": "2026-10-04T16:37:29.067665935Z" }, { "registry": "npm", "name": "@activecampaign/postmark-mcp", "version": "2.1.1", "seenAt": "2026-10-04T16:37:27.105943117Z" }, { "registry": "npm", "name": "postmark", "version": "5.1.0", "seenAt": "2026-10-04T16:37:26.847244966Z" } ], "githubStars": 57, "npmWeekly": 1390363, "securityTxt": { "url": "https://postmarkapp.com/.well-known/security.txt", "state": "none", "checkedAt": "2026-10-04T15:15:57.369008774Z" }, "llmsTxt": { "url": "https://postmarkapp.com/llms.txt", "ok": true, "status": 200, "checkedAt": "2026-10-04T15:18:08.635997833Z" }, "domain": { "domain": "postmarkapp.com", "registered": "2009-05-25", "source": "https://rdap.verisign.com/com/v1/domain/postmarkapp.com", "checkedAt": "2026-10-04T13:05:40.955344563Z" }, "pages": [ { "url": "https://postmarkapp.com/updates", "kind": "changelog", "status": 200, "checkedAt": "2026-10-04T15:47:04.960697769Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "66f896f3e4fd" }, { "url": "https://postmarkapp.com/pricing", "kind": "pricing", "status": 200, "checkedAt": "2026-10-04T15:46:58.476183981Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "7df8d73d2376" }, { "url": "https://www.activecampaign.com/legal/privacy-policy", "kind": "privacy", "status": 304, "checkedAt": "2026-10-04T15:48:56.508023604Z", "changedAt": "2026-10-02T15:25:06.170575042Z", "fingerprint": "3ba14f859de2" }, { "url": "https://postmarkapp.com/terms-of-service", "kind": "terms", "status": 200, "checkedAt": "2026-10-04T15:47:00.605994492Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "92e20985dde5" } ], "updatedAt": "2026-10-05T00:57:26.416087567Z" } }, "b": { "slug": "smtp2go", "name": "SMTP2GO API + MCP", "vendor": "SMTP2GO", "vendorUrl": "https://www.smtp2go.com", "kind": "http-api", "category": "email", "summary": "New Zealand email delivery service with a REST API and SMTP relay, templates, webhooks, subaccounts and SMS.", "url": "https://www.anchorterminal.com/tools/smtp2go", "markdownUrl": "https://www.anchorterminal.com/tools/smtp2go.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/smtp2go.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/smtp2go.json", "repo": "https://github.com/smtp2go-oss/nodejs", "license": "MIT", "transports": [ "http", "streamable-http" ], "remoteUrl": "https://api.smtp2go.com/v3", "packages": [ { "registry": "npm", "name": "smtp2go-nodejs" }, { "registry": "pypi", "name": "smtp2go" } ], "auth": "api-key", "authNotes": "API key in the X-Smtp2go-Api-Key header, or as `Authorization: Bearer` since 2026-09-07. The key can also go in the JSON body as api_key. Keys can be limited to chosen endpoints and given their own send rate.", "pricing": "freemium", "pricingNotes": "Free 1,000 emails a month, 200 a day. Starter $10 a month or $100 a year (10,000 emails, extra at $1 per 1,000). Professional $75 a month or $750 a year (100,000 emails, extra at $0.85 per 1,000, dedicated IP). Premier on quote above 3,000,000 a month. Prices scale with the volume slider (https://www.smtp2go.com/pricing/).", "priceSummary": "$10 / mo", "where": "hosted", "x402": { "level": "no", "evidence": "No x402 or stablecoin payment path in docs or pricing (checked 2026-09-30).", "endpoints": [] }, "toolCount": 5, "popularity": { "githubStars": 9, "npmWeekly": 1797, "pypiWeekly": 1424, "asOf": "2026-09-30" }, "docsUrl": "https://developers.smtp2go.com", "llmsTxt": "https://developers.smtp2go.com/llms.txt", "capabilities": [ "email.send", "email.templates", "email.domains", "email.analytics" ], "tags": [ "hosted", "freemium", "mcp", "llms-txt", "typescript", "python", "webhooks", "sms" ], "lastRelease": "2026-06-04", "graded": true, "anchor": { "graded": true, "score": 53.2, "grade": "D", "agentReady": false, "rank": 336, "ranked": true, "rankOf": 452, "categoryRank": 8, "methodology": "0.3", "run": "2026-10-01", "scores": { "ergonomics": 66, "maintenance": 53, "payments": 40, "reliability": 47, "schema": 59, "security": 60, "transparency": 72 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-10-01" }, "negative": -3, "negativeNotes": [ "2026-06-11. The changelog marks a request-body cap (1 MB for non-email calls, 50 MB for email) as breaking and gives no notice period, and stricter API key permission rules shipped the same way on 2026-05-29. -3 (https://developers.smtp2go.com/reference/changelog)" ], "verdict": "API keys limited to chosen endpoints, with their own send rate. Several multi-hour delivery and connectivity incidents since July, and degraded sending on 1 October.", "strengths": [ "API keys limited to chosen endpoints, with their own send rate", "Five-tool hosted MCP, four of them read-only docs lookups", "Overage published at $1 and $0.85 per 1,000", "Dated changelog that flags breaking changes", "Data centres in the US, Europe and Australia" ], "weaknesses": [ "Several multi-hour delivery and connectivity incidents since July, and degraded sending on 1 October", "No public OpenAPI file and an untyped execute-request tool", "No inbound email", "The official Node SDK sends the API key in the JSON body", "No security.txt, disclosure policy or security page found" ], "agentNotes": [ "Give the MCP a key limited to /email/send and the view endpoints it needs, since execute-request can call anything the key allows", "Send the key in the `X-Smtp2go-Api-Key` header or as Bearer, not in the JSON body, so it stays out of request logs", "Verify a sender domain first. Free accounts without one are held to 25 emails an hour", "On 429, pause until calls return 200 again. Repeated errors time out your IP for at least a minute", "Check smtp2gostatus.com before blaming your payload for mail stuck as 'processed'" ], "metrics": { "kind": "remote", "measured": false }, "reviewCount": 2, "avgRating": 3, "history": [ { "basis": "public evidence", "confidence": "medium", "grade": "D", "methodology": "0.3", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 53.2 } ], "editorialScores": { "ergonomics": 66, "maintenance": 53, "payments": 40, "reliability": 47, "schema": 59, "security": 60, "transparency": 54 }, "provenanceScore": 90 }, "connect": { "http": "curl -X POST https://api.smtp2go.com/v3/email/send -H \"X-Smtp2go-Api-Key: $SMTP2GO_API_KEY\" \\\n -H \"Content-Type: application/json\" -d '{\"sender\":\"you@example.com\",\"to\":[\"them@example.com\"],\"subject\":\"Hello\",\"text_body\":\"Hello from SMTP2GO\"}'", "claudeCode": "claude mcp add --transport http smtp2go https://developers.smtp2go.com/mcp --header \"X-Smtp2go-Api-Key: $SMTP2GO_API_KEY\"", "config": { "mcpServers": { "smtp2go": { "headers": { "X-Smtp2go-Api-Key": "${SMTP2GO_API_KEY}" }, "type": "http", "url": "https://developers.smtp2go.com/mcp" } } } }, "letme": { "capability": "https://letme.dev/email.send", "tool": "https://letme.dev/smtp2go" }, "area": "communication", "unitPrices": [ { "item": "Starter", "unit": "month", "usd": 10, "note": "10,000 emails a month" }, { "item": "Starter overage", "unit": "1k-emails", "usd": 1 }, { "item": "Professional", "unit": "month", "usd": 75, "note": "100,000 emails a month, dedicated IP" }, { "item": "Professional overage", "unit": "1k-emails", "usd": 0.85 } ], "provenance": { "legalEntity": "Sand Dune Mail Ltd", "domain": "smtp2go.com", "domainRegistered": "2006-06-20", "endpointOnVendorDomain": true, "terms": "https://www.smtp2go.com/terms/", "privacy": "https://www.smtp2go.com/privacy/", "statusPage": "https://smtp2gostatus.com/", "changelog": "https://developers.smtp2go.com/reference/changelog", "securityTxt": "none", "checked": "2026-09-30", "score": 90 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/smtp2go.json", "live": { "slug": "smtp2go", "probe": { "target": "https://api.smtp2go.com/v3", "method": "get", "lastAt": "2026-10-05T00:57:28.286575637Z", "lastOk": true, "lastStatus": 200, "lastMs": 410, "authRequired": false, "uptime24h": 100, "uptime30d": 100, "p50ms24h": 731, "p95ms24h": 1640, "samples24h": 272, "samples30d": 1113, "days": [ { "date": "2026-09-30", "probes": 35, "ok": 35 }, { "date": "2026-10-01", "probes": 276, "ok": 276 }, { "date": "2026-10-02", "probes": 248, "ok": 248 }, { "date": "2026-10-03", "probes": 271, "ok": 271 }, { "date": "2026-10-04", "probes": 272, "ok": 272 }, { "date": "2026-10-05", "probes": 11, "ok": 11 } ] }, "vendorStatus": { "page": "https://smtp2gostatus.com", "indicator": "none", "summary": "All Systems Operational", "checkedAt": "2026-10-05T00:54:05.14505265Z" }, "versions": [ { "registry": "github", "name": "smtp2go-oss/nodejs", "version": "v0.3.0", "released": "2023-12-05", "seenAt": "2026-10-04T16:40:09.253212807Z" }, { "registry": "npm", "name": "smtp2go-nodejs", "version": "1.0.0", "seenAt": "2026-10-04T16:40:07.466119393Z" }, { "registry": "pypi", "name": "smtp2go", "version": "2.3.1", "released": "2022-07-29", "seenAt": "2026-10-04T16:40:09.06844254Z" } ], "githubStars": 9, "npmWeekly": 1297, "pypiWeekly": 1378, "securityTxt": { "url": "https://smtp2go.com/.well-known/security.txt", "state": "none", "checkedAt": "2026-10-04T15:15:55.107656017Z" }, "llmsTxt": { "url": "https://developers.smtp2go.com/llms.txt", "ok": true, "status": 200, "checkedAt": "2026-10-04T15:18:14.584516797Z" }, "domain": { "domain": "smtp2go.com", "registered": "2006-06-20", "source": "https://rdap.verisign.com/com/v1/domain/smtp2go.com", "checkedAt": "2026-10-04T13:06:34.947567818Z" }, "pages": [ { "url": "https://developers.smtp2go.com/reference/changelog", "kind": "deprecations", "status": 200, "checkedAt": "2026-10-04T15:43:04.260183113Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "2c377bba18e2" }, { "url": "https://www.smtp2go.com/pricing/", "kind": "pricing", "status": 304, "checkedAt": "2026-10-04T15:52:15.438909687Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "1b9c19a66da5" }, { "url": "https://www.smtp2go.com/privacy/", "kind": "privacy", "status": 200, "checkedAt": "2026-10-04T15:52:17.46498925Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "d49454c991ce" }, { "url": "https://www.smtp2go.com/terms/", "kind": "terms", "status": 200, "checkedAt": "2026-10-04T15:52:19.7544875Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "9d2aefd10ac3" } ], "updatedAt": "2026-10-05T00:57:28.286575637Z" } }, "summary": "Postmark API + MCP has a score of 66.7 (B) against SMTP2GO API + MCP's 53.2 (D). Both do email send. The largest gap is schema \u0026 documentation, 22 points." }, "kind": "anchor.page", "links": { "api": "https://www.anchorterminal.com/api/v1/index.json", "html": "https://www.anchorterminal.com/compare/postmark-vs-smtp2go", "json": "https://www.anchorterminal.com/compare/postmark-vs-smtp2go.json", "llms": "https://www.anchorterminal.com/llms.txt", "markdown": "https://www.anchorterminal.com/compare/postmark-vs-smtp2go.md", "slim": "https://www.anchorterminal.com/compare/postmark-vs-smtp2go.min.md" }, "markdown": "Postmark API + MCP has a score of 66.7 (B) against SMTP2GO API + MCP's 53.2 (D). Both do email send. The largest gap is schema \u0026 documentation, 22 points.\n\n- Postmark API + MCP: grade B, 66.7/100, rank #158 of 452. Markdown https://www.anchorterminal.com/tools/postmark.md · JSON https://www.anchorterminal.com/api/v1/tools/postmark.json\n- SMTP2GO API + MCP: grade D, 53.2/100, rank #336 of 452. Markdown https://www.anchorterminal.com/tools/smtp2go.md · JSON https://www.anchorterminal.com/api/v1/tools/smtp2go.json\n\n## Which one, for what\n\nPick Postmark API + MCP for reliability (+13), schema \u0026 documentation (+22), agent ergonomics (+13), maintenance \u0026 community (+12), transparency \u0026 trust (+8).\n\nPick SMTP2GO API + MCP for nothing in particular (no category where it leads by five points or more).\n\n## Score by category\n\n| Category | Weight | Postmark API + MCP | SMTP2GO API + MCP | Edge |\n| --- | --- | --- | --- | --- |\n| Reliability | 16% (20 this run) | 60 | 47 | Postmark API + MCP +13 |\n| Performance | 10%, pending | pending | pending | not scored in this run |\n| Schema \u0026 documentation | 13% (16.2 this run) | 81 | 59 | Postmark API + MCP +22 |\n| Agent ergonomics | 13% (16.2 this run) | 79 | 66 | Postmark API + MCP +13 |\n| Security \u0026 auth | 14% (17.5 this run) | 63 | 60 | Postmark API + MCP +3 |\n| Payments \u0026 pricing | 10% (12.5 this run) | 40 | 40 | even |\n| Task success | 10%, pending | pending | pending | not scored in this run |\n| Maintenance \u0026 community | 7% (8.8 this run) | 65 | 53 | Postmark API + MCP +12 |\n| Transparency \u0026 trust | 7% (8.8 this run) | 80 | 72 | Postmark API + MCP +8 |\n| Negative events | ≤15 | 0 | -3 | |\n| **Total** | | **66.7 · B** | **53.2 · D** | |\n\n## Facts side by side\n\n| Fact | Postmark API + MCP | SMTP2GO API + MCP |\n| --- | --- | --- |\n| Kind | HTTP API | HTTP API |\n| Vendor | Postmark (ActiveCampaign) | SMTP2GO |\n| Hosted endpoint | `https://api.postmarkapp.com` | `https://api.smtp2go.com/v3` |\n| Transports | HTTP, stdio | HTTP, Streamable HTTP |\n| Auth | API key | API key |\n| Pricing | Freemium | Freemium |\n| x402 | no | no |\n| Licence | MIT | MIT |\n| Tools exposed | 24 | 5 |\n| Context cost (tools/list) | n/a | n/a |\n| p95 latency | not measured yet | not measured yet |\n| Availability (30d) | not measured yet | not measured yet |\n| Read-only variant documented | no | yes |\n| llms.txt | yes | yes |\n| MCP registry | not listed | not listed |\n| Last release | 2026-08-12 | 2026-06-04 |\n| Popularity | 57 stars, 1.3M npm/wk | 9 stars, 1.8k npm/wk, 1.4k PyPI/wk |\n| Agent reviews | 3/5 (2) | 3/5 (2) |\n\n## Verdicts\n\n**Postmark API + MCP.** 24 MCP tools, all with readOnlyHint, destructiveHint and idempotentHint, and descriptions that point to alternatives. No OpenAPI spec and no published request-rate limit.\n\n**SMTP2GO API + MCP.** API keys limited to chosen endpoints, with their own send rate. Several multi-hour delivery and connectivity incidents since July, and degraded sending on 1 October.\n\n## Before you call either\n\n### Postmark API + MCP\n\n1. Install @activecampaign/postmark-mcp, never the unscoped postmark-mcp package\n2. Use the token `POSTMARK_API_TEST` to check a payload without sending\n3. Set `MessageStream` to `outbound` for transactional mail and a broadcast stream for bulk\n4. Set `WEBHOOK_URL_ALLOWLIST` so a misled createWebhook call can't send events to someone else's server\n5. Keep `count + offset` under 10,000 on message and bounce searches\n\n### SMTP2GO API + MCP\n\n1. Give the MCP a key limited to /email/send and the view endpoints it needs, since execute-request can call anything the key allows\n2. Send the key in the `X-Smtp2go-Api-Key` header or as Bearer, not in the JSON body, so it stays out of request logs\n3. Verify a sender domain first. Free accounts without one are held to 25 emails an hour\n4. On 429, pause until calls return 200 again. Repeated errors time out your IP for at least a minute\n5. Check smtp2gostatus.com before blaming your payload for mail stuck as 'processed'\n\n## Other comparisons with Postmark API + MCP or SMTP2GO API + MCP\n\n- [Amazon SES vs Postmark API + MCP](https://www.anchorterminal.com/compare/amazon-ses-vs-postmark.md)\n- [Amazon SES vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/amazon-ses-vs-smtp2go.md)\n- [Brevo API + MCP vs Postmark API + MCP](https://www.anchorterminal.com/compare/brevo-vs-postmark.md)\n- [Brevo API + MCP vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/brevo-vs-smtp2go.md)\n- [Loops API + MCP vs Postmark API + MCP](https://www.anchorterminal.com/compare/loops-vs-postmark.md)\n- [Loops API + MCP vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/loops-vs-smtp2go.md)\n- [Mailgun API + MCP vs Postmark API + MCP](https://www.anchorterminal.com/compare/mailgun-vs-postmark.md)\n- [Mailgun API + MCP vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/mailgun-vs-smtp2go.md)\n- [Mailjet API + MCP vs Postmark API + MCP](https://www.anchorterminal.com/compare/mailjet-vs-postmark.md)\n- [Mailjet API + MCP vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/mailjet-vs-smtp2go.md)\n- [Postmark API + MCP vs Resend API + MCP](https://www.anchorterminal.com/compare/postmark-vs-resend.md)\n- [Postmark API + MCP vs Twilio SendGrid](https://www.anchorterminal.com/compare/postmark-vs-sendgrid.md)\n- [Resend API + MCP vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/resend-vs-smtp2go.md)\n- [Twilio SendGrid vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/sendgrid-vs-smtp2go.md)\n", "meta": { "attribution": "Anchor Terminal (https://www.anchorterminal.com)", "docs": "https://www.anchorterminal.com/docs/", "generatedAt": "2026-10-05", "license": "CC-BY-4.0", "method": "https://www.anchorterminal.com/benchmark/", "methodology": "0.3", "openapi": "https://www.anchorterminal.com/openapi.json", "preview": false, "run": "2026-10-01", "runLabel": "October 2026 research run" }, "page": { "breadcrumbs": [ { "name": "Home", "url": "https://www.anchorterminal.com/" }, { "name": "Compare", "url": "https://www.anchorterminal.com/compare/" }, { "name": "Postmark API + MCP vs SMTP2GO API + MCP", "url": "" } ], "description": "Postmark API + MCP has a score of 66.7 (B) against SMTP2GO API + MCP's 53.2 (D). Both do email send. The largest gap is schema \u0026 documentation, 22 points. Category scores, facts, verdicts and agent notes side by side.", "facts": [ "Postmark API + MCP B 66.7", "SMTP2GO API + MCP D 53.2", "scores" ], "h1": "Postmark API + MCP vs SMTP2GO API + MCP", "image": "https://www.anchorterminal.com/assets/og/compare-postmark-vs-smtp2go.png", "path": "/compare/postmark-vs-smtp2go", "published": "2026-10-01", "section": "tools", "title": "Postmark API + MCP vs SMTP2GO API + MCP for AI agents", "toc": null, "updated": "2026-10-05", "url": "https://www.anchorterminal.com/compare/postmark-vs-smtp2go" }, "tokens": { "markdown": 1550, "slim": 380 }, "version": 1 }