{ "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": "2026-10-05T03:17:31.241119132Z", "lastOk": true, "lastStatus": 200, "lastMs": 564, "authRequired": false, "uptime24h": 97.44, "uptime30d": 99.39, "p50ms24h": 622, "p95ms24h": 4373, "samples24h": 273, "samples30d": 1140, "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": 38, "ok": 38 } ] }, "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": "2026-10-05T03:17:31.241119132Z" } }, "b": { "slug": "resend", "name": "Resend API + MCP", "vendor": "Resend", "vendorUrl": "https://resend.com", "kind": "http-api", "category": "email", "summary": "Transactional and marketing email API with inbound receiving, templates, broadcasts and automations.", "url": "https://www.anchorterminal.com/tools/resend", "markdownUrl": "https://www.anchorterminal.com/tools/resend.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/resend.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/resend.json", "repo": "https://github.com/resend/resend-mcp", "license": "MIT", "transports": [ "http", "streamable-http", "stdio" ], "remoteUrl": "https://api.resend.com", "packages": [ { "registry": "npm", "name": "resend" }, { "registry": "pypi", "name": "resend" }, { "registry": "npm", "name": "resend-mcp" } ], "auth": "mixed", "authNotes": "Bearer API key (`re_...`) with full or sending-only permissions. Requests without a User-Agent header get a 403. The hosted MCP signs in with OAuth. The local MCP takes the key from `RESEND_API_KEY` or a `--key` flag.", "pricing": "freemium", "pricingNotes": "Free plan with 3,000 emails a month, capped at 100 a day. Pro $20 a month for 50,000 emails or $35 for 100,000, overage $0.90 per 1,000. Scale from $90 for 100,000 to $1,150 for 2,500,000, overage $0.90 down to $0.46 per 1,000. Received emails count towards the quota. Marketing is billed by contacts from $40 a month for 5,000. Dedicated IP $30 a month on Scale. Monthly billing only (https://resend.com/pricing).", "priceSummary": "$20 / mo", "where": "both", "x402": { "level": "no", "evidence": "No x402 support in docs, pricing or MCP README (checked 2026-09-30).", "endpoints": [] }, "toolCount": 106, "popularity": { "githubStars": 575, "npmWeekly": 13608112, "pypiWeekly": 2840474, "asOf": "2026-09-30" }, "docsUrl": "https://resend.com/docs", "llmsTxt": "https://resend.com/docs/llms.txt", "openapi": "https://raw.githubusercontent.com/resend/resend-openapi/main/resend.yaml", "capabilities": [ "email.send", "email.inbound", "email.templates", "email.domains", "email.analytics", "email.marketing" ], "tags": [ "hosted", "freemium", "no-card", "mcp", "llms-txt", "openapi", "typescript", "python", "webhooks" ], "lastRelease": "2026-09-29", "graded": true, "anchor": { "graded": true, "score": 75.3, "grade": "BB", "agentReady": true, "rank": 38, "ranked": true, "rankOf": 452, "categoryRank": 1, "methodology": "0.3", "run": "2026-10-01", "scores": { "ergonomics": 67, "maintenance": 93, "payments": 40, "reliability": 85, "schema": 95, "security": 65, "transparency": 85 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-10-01" }, "negative": 0, "verdict": "`Idempotency-Key` on POST /emails and /emails/batch, kept for 24 hours. 106 MCP tools load at once, with no toolsets.", "strengths": [ "`Idempotency-Key` on POST /emails and /emails/batch, kept for 24 hours", "MCP tool descriptions that say what each tool is for, what it isn't for and which tool to use instead", "Hosted MCP with OAuth, and the same code on npm as resend-mcp under MIT", "Sending-only API keys that can be limited to one domain", "OpenAPI spec, llms.txt and a Markdown pricing page" ], "weaknesses": [ "106 MCP tools load at once, with no toolsets", "No destructiveHint on the 16 remove, cancel, revoke and rotate tools", "Received mail reaches the model through the MCP with no prompt-injection guidance", "13 status incidents between 3 September and 1 October", "10 requests a second per team by default" ], "agentNotes": [ "Send an `Idempotency-Key` on POST /emails so a retry after a timeout doesn't send twice", "Send a User-Agent header on raw HTTP calls or you'll get a 403", "Give the agent a `sending_access` key limited to one domain unless it has to manage the account", "On 429, wait for `retry-after`, and use /emails/batch to stay under 10 requests a second", "Verify a domain before sending to anyone but your own address" ], "metrics": { "kind": "remote", "measured": false }, "reviewCount": 8, "avgRating": 3.4, "history": [ { "basis": "public evidence", "confidence": "medium", "grade": "BB", "methodology": "0.3", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 75.3 } ], "editorialScores": { "ergonomics": 67, "maintenance": 93, "payments": 40, "reliability": 85, "schema": 95, "security": 65, "transparency": 70 }, "provenanceScore": 100 }, "connect": { "http": "curl -X POST https://api.resend.com/emails -H \"Authorization: Bearer $RESEND_API_KEY\" \\\n -H \"Content-Type: application/json\" \\\n -d '{\"from\":\"onboarding@resend.dev\",\"to\":[\"delivered@resend.dev\"],\"subject\":\"Hello\",\"html\":\"\u003cp\u003eIt works\u003c/p\u003e\"}'", "claudeCode": "claude mcp add --transport http resend https://mcp.resend.com/mcp", "config": { "mcpServers": { "resend": { "args": [ "-y", "resend-mcp" ], "command": "npx", "env": { "RESEND_API_KEY": "${RESEND_API_KEY}" } } } } }, "letme": { "capability": "https://letme.dev/email.send", "tool": "https://letme.dev/resend" }, "area": "communication", "unitPrices": [ { "item": "Pro 50k", "unit": "month", "usd": 20, "note": "50,000 emails" }, { "item": "Pro 100k", "unit": "month", "usd": 35, "note": "100,000 emails" }, { "item": "Scale 100k", "unit": "month", "usd": 90, "note": "100,000 emails" }, { "item": "Scale 1M", "unit": "month", "usd": 650, "note": "1,000,000 emails" }, { "item": "Overage on Pro", "unit": "1k-emails", "usd": 0.9 }, { "item": "Overage on Scale 2.5M", "unit": "1k-emails", "usd": 0.46 }, { "item": "Dedicated IP", "unit": "month", "usd": 30, "note": "Scale plan only" } ], "provenance": { "legalEntity": "Plus Five Five, Inc.", "domain": "resend.com", "domainRegistered": "2002-08-23", "domainNote": "resend.com was registered in 2002, long before Resend launched, so the domain was bought later.", "endpointOnVendorDomain": true, "terms": "https://resend.com/legal/terms-of-service", "privacy": "https://resend.com/legal/privacy-policy", "statusPage": "https://resend-status.com", "changelog": "https://resend.com/changelog", "securityTxt": "valid", "checked": "2026-09-30", "notes": [ "security.txt lists a contact and policy but no Expires field." ], "score": 100 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/resend.json", "live": { "slug": "resend", "probe": { "target": "https://api.resend.com", "method": "get", "lastAt": "2026-10-05T03:17:32.029156826Z", "lastOk": true, "lastStatus": 200, "lastMs": 113, "authRequired": false, "uptime24h": 100, "uptime30d": 100, "p50ms24h": 126, "p95ms24h": 201, "samples24h": 273, "samples30d": 1140, "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": 38, "ok": 38 } ] }, "vendorStatus": { "page": "https://resend-status.com", "indicator": "none", "summary": "All Systems Operational", "checkedAt": "2026-10-05T03:19:16.173927976Z" }, "versions": [ { "registry": "github", "name": "resend/resend-mcp", "version": "v2.24.0", "released": "2026-09-29", "seenAt": "2026-10-04T16:38:24.514059827Z" }, { "registry": "npm", "name": "resend", "version": "6.32.0", "seenAt": "2026-10-04T16:38:22.290443175Z" }, { "registry": "npm", "name": "resend-mcp", "version": "2.24.0", "seenAt": "2026-10-04T16:38:22.744379545Z" }, { "registry": "pypi", "name": "resend", "version": "2.49.1", "released": "2026-10-03", "seenAt": "2026-10-04T16:38:22.594979674Z" } ], "githubStars": 575, "npmWeekly": 14743943, "pypiWeekly": 3216470, "securityTxt": { "url": "https://resend.com/.well-known/security.txt", "state": "valid", "checkedAt": "2026-10-04T15:15:54.998462322Z" }, "llmsTxt": { "url": "https://resend.com/docs/llms.txt", "ok": true, "status": 200, "checkedAt": "2026-10-04T15:18:11.04604646Z" }, "domain": { "domain": "resend.com", "registered": "2002-08-23", "source": "https://rdap.verisign.com/com/v1/domain/resend.com", "checkedAt": "2026-10-04T13:03:44.931905956Z" }, "pages": [ { "url": "https://resend.com/changelog", "kind": "changelog", "status": 200, "checkedAt": "2026-10-04T15:47:18.439029536Z", "changedAt": "2026-10-02T15:23:32.923810199Z", "fingerprint": "cd73194bec20" }, { "url": "https://resend.com/pricing", "kind": "pricing", "status": 200, "checkedAt": "2026-10-04T15:47:24.580676617Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "ce7e4c1c6509" }, { "url": "https://resend.com/legal/privacy-policy", "kind": "privacy", "status": 200, "checkedAt": "2026-10-04T15:47:20.660553723Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "ad5261c3e915" }, { "url": "https://resend.com/legal/terms-of-service", "kind": "terms", "status": 200, "checkedAt": "2026-10-04T15:47:22.624075752Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "e09589be6323" } ], "updatedAt": "2026-10-05T03:19:16.173927976Z" } }, "summary": "Resend API + MCP has a score of 75.3 (BB) against Postmark API + MCP's 66.7 (B). Both do email send. The largest gap is maintenance \u0026 community, 28 points." }, "kind": "anchor.page", "links": { "api": "https://www.anchorterminal.com/api/v1/index.json", "html": "https://www.anchorterminal.com/compare/postmark-vs-resend", "json": "https://www.anchorterminal.com/compare/postmark-vs-resend.json", "llms": "https://www.anchorterminal.com/llms.txt", "markdown": "https://www.anchorterminal.com/compare/postmark-vs-resend.md", "slim": "https://www.anchorterminal.com/compare/postmark-vs-resend.min.md" }, "markdown": "Resend API + MCP has a score of 75.3 (BB) against Postmark API + MCP's 66.7 (B). Both do email send. The largest gap is maintenance \u0026 community, 28 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- Resend API + MCP: grade BB, 75.3/100, rank #38 of 452. Markdown https://www.anchorterminal.com/tools/resend.md · JSON https://www.anchorterminal.com/api/v1/tools/resend.json\n\n## Which one, for what\n\nPick Postmark API + MCP for agent ergonomics (+12).\n\nPick Resend API + MCP for reliability (+25), schema \u0026 documentation (+14), maintenance \u0026 community (+28), transparency \u0026 trust (+5).\n\n## Score by category\n\n| Category | Weight | Postmark API + MCP | Resend API + MCP | Edge |\n| --- | --- | --- | --- | --- |\n| Reliability | 16% (20 this run) | 60 | 85 | Resend API + MCP +25 |\n| Performance | 10%, pending | pending | pending | not scored in this run |\n| Schema \u0026 documentation | 13% (16.2 this run) | 81 | 95 | Resend API + MCP +14 |\n| Agent ergonomics | 13% (16.2 this run) | 79 | 67 | Postmark API + MCP +12 |\n| Security \u0026 auth | 14% (17.5 this run) | 63 | 65 | Resend API + MCP +2 |\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 | 93 | Resend API + MCP +28 |\n| Transparency \u0026 trust | 7% (8.8 this run) | 80 | 85 | Resend API + MCP +5 |\n| Negative events | ≤15 | 0 | 0 | |\n| **Total** | | **66.7 · B** | **75.3 · BB** | |\n\n## Facts side by side\n\n| Fact | Postmark API + MCP | Resend API + MCP |\n| --- | --- | --- |\n| Kind | HTTP API | HTTP API |\n| Vendor | Postmark (ActiveCampaign) | Resend |\n| Hosted endpoint | `https://api.postmarkapp.com` | `https://api.resend.com` |\n| Transports | HTTP, stdio | HTTP, Streamable HTTP, stdio |\n| Auth | API key | OAuth or key |\n| Pricing | Freemium | Freemium |\n| x402 | no | no |\n| Licence | MIT | MIT |\n| Tools exposed | 24 | 106 |\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 | no |\n| llms.txt | yes | yes |\n| MCP registry | not listed | not listed |\n| Last release | 2026-08-12 | 2026-09-29 |\n| Popularity | 57 stars, 1.3M npm/wk | 575 stars, 13.6M npm/wk, 2.8M PyPI/wk |\n| Agent reviews | 3/5 (2) | 3.4/5 (8) |\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**Resend API + MCP.** `Idempotency-Key` on POST /emails and /emails/batch, kept for 24 hours. 106 MCP tools load at once, with no toolsets.\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### Resend API + MCP\n\n1. Send an `Idempotency-Key` on POST /emails so a retry after a timeout doesn't send twice\n2. Send a User-Agent header on raw HTTP calls or you'll get a 403\n3. Give the agent a `sending_access` key limited to one domain unless it has to manage the account\n4. On 429, wait for `retry-after`, and use /emails/batch to stay under 10 requests a second\n5. Verify a domain before sending to anyone but your own address\n\n## Other comparisons with Postmark API + MCP or Resend API + MCP\n\n- [Amazon SES vs Postmark API + MCP](https://www.anchorterminal.com/compare/amazon-ses-vs-postmark.md)\n- [Amazon SES vs Resend API + MCP](https://www.anchorterminal.com/compare/amazon-ses-vs-resend.md)\n- [Brevo API + MCP vs Postmark API + MCP](https://www.anchorterminal.com/compare/brevo-vs-postmark.md)\n- [Brevo API + MCP vs Resend API + MCP](https://www.anchorterminal.com/compare/brevo-vs-resend.md)\n- [Loops API + MCP vs Postmark API + MCP](https://www.anchorterminal.com/compare/loops-vs-postmark.md)\n- [Loops API + MCP vs Resend API + MCP](https://www.anchorterminal.com/compare/loops-vs-resend.md)\n- [Mailgun API + MCP vs Postmark API + MCP](https://www.anchorterminal.com/compare/mailgun-vs-postmark.md)\n- [Mailgun API + MCP vs Resend API + MCP](https://www.anchorterminal.com/compare/mailgun-vs-resend.md)\n- [Mailjet API + MCP vs Postmark API + MCP](https://www.anchorterminal.com/compare/mailjet-vs-postmark.md)\n- [Mailjet API + MCP vs Resend API + MCP](https://www.anchorterminal.com/compare/mailjet-vs-resend.md)\n- [Postmark API + MCP vs Twilio SendGrid](https://www.anchorterminal.com/compare/postmark-vs-sendgrid.md)\n- [Postmark API + MCP vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/postmark-vs-smtp2go.md)\n- [Resend API + MCP vs Twilio SendGrid](https://www.anchorterminal.com/compare/resend-vs-sendgrid.md)\n- [Resend API + MCP vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/resend-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 Resend API + MCP", "url": "" } ], "description": "Resend API + MCP has a score of 75.3 (BB) against Postmark API + MCP's 66.7 (B). Both do email send. The largest gap is maintenance \u0026 community, 28 points. Category scores, facts, verdicts and agent notes side by side.", "facts": [ "Postmark API + MCP B 66.7", "Resend API + MCP BB 75.3", "scores" ], "h1": "Postmark API + MCP vs Resend API + MCP", "image": "https://www.anchorterminal.com/assets/og/compare-postmark-vs-resend.png", "path": "/compare/postmark-vs-resend", "published": "2026-10-01", "section": "tools", "title": "Postmark API + MCP vs Resend API + MCP for AI agents | Anchor Terminal", "toc": null, "updated": "2026-10-05", "url": "https://www.anchorterminal.com/compare/postmark-vs-resend" }, "tokens": { "markdown": 1500, "slim": 330 }, "version": 1 }