{ "data": { "a": { "slug": "groundmail", "name": "Groundmail API + MCP", "vendor": "Groundmail", "vendorUrl": "https://groundmail.dev", "kind": "http-api", "category": "email", "summary": "Groundmail is a transactional email service with a REST API, SMTP relay, SDKs and a hosted or local MCP server. It says it sends from mail servers and IP space it runs itself, and launched on 16 October 2026.", "url": "https://www.anchorterminal.com/tools/groundmail", "markdownUrl": "https://www.anchorterminal.com/tools/groundmail.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/groundmail.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/groundmail.json", "repo": "https://github.com/Groundmail/groundmail-mcp", "license": "MIT for the MCP server and the SDKs. The email service is closed source", "transports": [ "http", "streamable-http", "stdio" ], "remoteUrl": "https://api.groundmail.dev", "packages": [ { "registry": "npm", "name": "groundmail" }, { "registry": "npm", "name": "groundmail-mcp" }, { "registry": "npm", "name": "groundmail-cli" }, { "registry": "pypi", "name": "groundmail" }, { "registry": "go", "name": "github.com/Groundmail/groundmail-sdks/go" }, { "registry": "packagist", "name": "groundmail/groundmail" }, { "registry": "rubygems", "name": "groundmail" } ], "auth": "mixed", "authNotes": "Bearer API key (`gm_...`) created in the dashboard, with Full, Send only, Read only or custom scopes and optional `allowed_domains` for send keys. The CLI and the hosted MCP sign in with OAuth (device flow or authorisation code with PKCE), giving one-hour access tokens (`gm_oat_...`) and rotating refresh tokens. The SMTP relay uses separate `gmsmtp_...` credentials.", "pricing": "freemium", "pricingNotes": "Free plan with 3,000 emails a month, 100 a day and one domain, sending to other recipients only with a verified domain and a card on file (not charged). Pro from $20 a month for 50,000 emails, overage $0.90 per 1,000. Scale from $90 for 100,000 to $1,150 for 2,500,000, overage down to $0.46 per 1,000. Dedicated server from $299 a month with 250,000 emails. Dedicated IPs $50 a month each on Scale. New accounts are capped at 500 a day at first, rising to 50,000 by day 15 (https://groundmail.dev/pricing/).", "priceSummary": "$20 / mo", "where": "both", "x402": { "level": "no", "evidence": "No x402, MPP or L402 in llms-full.txt, the OpenAPI document or the pricing page (checked 2026-10-17). Billing is through Stripe.", "endpoints": [] }, "toolCount": 20, "popularity": { "githubStars": null, "npmWeekly": null, "pypiWeekly": null, "asOf": "2026-10-17" }, "docsUrl": "https://docs.groundmail.dev", "llmsTxt": "https://docs.groundmail.dev/llms.txt", "openapi": "https://docs.groundmail.dev/openapi.yaml", "registryName": "io.github.Groundmail/groundmail", "capabilities": [ "email.send", "email.domains", "email.templates", "email.inbound", "email.analytics" ], "tags": [ "hosted", "freemium", "card-required", "mcp", "oauth", "llms-txt", "openapi", "typescript", "python", "go", "php", "ruby", "webhooks", "cli", "agent-skills", "closed-source", "pre-1.0", "new" ], "lastRelease": "2026-10-17", "graded": true, "anchor": { "graded": true, "score": 57.6, "grade": "C", "agentReady": false, "rank": 665, "ranked": true, "rankOf": 1133, "categoryRank": 14, "methodology": "0.4", "run": "2026-10-01", "scores": { "ergonomics": 79, "maintenance": 72, "payments": 35, "reliability": 38, "schema": 77, "security": 56, "transparency": 48 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-10-17" }, "negative": 0, "verdict": "Groundmail pairs scoped API keys and OAuth with stable error codes, recovery hints and `Idempotency-Key` on sends, and its 20 MCP tools carry safety annotations. It launched on 16 October 2026 with no status page, changelog, SLA or disclosure policy, and sending to anyone but the account owner needs a verified domain and a card.", "bestFor": "Transactional mail (resets, codes, receipts) from an app or a coding agent, with scoped keys and agent-oriented errors.", "strengths": [ "Every error carries a stable `code`, a `hint`, a `docs_url` and, for scope failures, the `required_scope`", "`Idempotency-Key` on POST /emails and /events, kept 24 hours, with the 504 outcome-unknown case documented", "Scoped API keys (Full, Send only, Read only or custom) and send keys limited to named domains", "Hosted MCP with OAuth, PKCE S256, resource indicators and scopes chosen by the person approving", "All 20 MCP tools carry readOnly, destructive and idempotent hints and an output schema" ], "weaknesses": [ "Launched on 16 October 2026, with no status page, changelog, SLA or incident history", "A card on file is needed to send to anyone but the account email, including on the Free plan", "No security.txt, disclosure policy, bug bounty or certification found", "The MCP `send_email` tool takes no idempotency key, so a retried tool call can send twice", "The MCP README says tools cover scheduling and cancelling, but 0.6.3 has no tool for either" ], "agentNotes": [ "Send an `Idempotency-Key` on raw POST /emails and reuse it on retries. On 504, check GET /emails before sending again", "Test from `noreply@mail.groundmail.dev` to the account email only. Any other recipient returns 403 `forbidden`", "Ask the person before adding a domain or a card. Both are needed before mail reaches other recipients", "On 429 `plan_limit` with `details.reason: \"warmup\"`, wait until `details.resets_at`. Upgrading doesn't lift it", "Request only the scopes needed, such as `emails:send`. An OAuth request with no scope gets `full`" ], "metrics": { "kind": "remote", "measured": false }, "reviewCount": 4, "avgRating": 2.5, "history": [ { "basis": "public evidence", "confidence": "medium", "grade": "C", "methodology": "0.4", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 57.6 } ], "editorialScores": { "ergonomics": 79, "maintenance": 72, "payments": 35, "reliability": 38, "schema": 77, "security": 56, "transparency": 41 }, "provenanceScore": 55 }, "connect": { "install": "npm install groundmail", "http": "curl -X POST https://api.groundmail.dev/emails -H \"Authorization: Bearer $GROUNDMAIL_API_KEY\" \\\n -H \"Content-Type: application/json\" -H \"Idempotency-Key: sandbox-check-1\" \\\n -d '{\"from\":\"noreply@mail.groundmail.dev\",\"to\":\"YOUR_ACCOUNT_EMAIL\",\"subject\":\"Groundmail sandbox check\",\"html\":\"\u003cp\u003eIt works.\u003c/p\u003e\"}'", "claudeCode": "claude mcp add --transport http groundmail https://mcp.groundmail.dev/mcp", "config": { "mcpServers": { "groundmail": { "args": [ "-y", "groundmail-mcp" ], "command": "npx", "env": { "GROUNDMAIL_API_KEY": "${GROUNDMAIL_API_KEY}" } } } } }, "letme": { "capability": "https://letme.dev/email.send", "tool": "https://letme.dev/groundmail" }, "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 server", "unit": "month", "usd": 299, "note": "250,000 emails included, $0.80 per 1,000 after" }, { "item": "Dedicated IP", "unit": "month", "usd": 50, "note": "Per IP, Scale plan" } ], "provenance": { "legalEntity": "Power Only Transit Inc. dba Groundmail", "domain": "groundmail.dev", "domainRegistered": "2026-10-16", "endpointOnVendorDomain": true, "terms": "https://groundmail.dev/legal/terms/", "privacy": "https://groundmail.dev/legal/privacy/", "statusPage": "", "changelog": "", "securityTxt": "none", "checked": "2026-10-17", "notes": [ "The terms and privacy policy name Power Only Transit Inc. dba Groundmail, 2780 S. Jones Blvd #200-3432, Las Vegas, NV 89146, and Delaware law.", "RDAP gives groundmail.dev a registration time of 2026-10-16T03:15Z. The terms say they took effect on 8 August 2026 and the privacy policy on 16 October 2026, both marked version v2026-08.", "security.txt answered 404 on groundmail.dev and docs.groundmail.dev. status.groundmail.dev doesn't resolve, and groundmail.dev/status, docs.groundmail.dev/changelog and groundmail.dev/security/ answer 404.", "robots.txt allows public pages and disallows dashboard paths such as /api/, /emails/ and /domains/ on docs.groundmail.dev. Only allowed paths were read." ], "score": 55 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/groundmail.json", "live": { "slug": "groundmail", "probe": { "target": "https://api.groundmail.dev", "method": "get", "lastAt": "2026-10-18T00:14:41.979024896Z", "lastOk": true, "lastStatus": 200, "lastMs": 648, "authRequired": false, "uptime24h": 100, "uptime30d": 100, "p50ms24h": 677, "p95ms24h": 810, "samples24h": 24, "samples30d": 24, "days": [ { "date": "2026-10-17", "probes": 21, "ok": 21 }, { "date": "2026-10-18", "probes": 3, "ok": 3 } ] }, "pages": [ { "url": "https://groundmail.dev/pricing/", "kind": "pricing", "status": 200, "checkedAt": "2026-10-17T23:03:51.382426956Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "d31886163215" }, { "url": "https://groundmail.dev/legal/privacy/", "kind": "privacy", "status": 200, "checkedAt": "2026-10-17T23:03:47.325144117Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "b568fc16407f" }, { "url": "https://groundmail.dev/legal/terms/", "kind": "terms", "status": 200, "checkedAt": "2026-10-17T23:03:49.387195166Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "b4c6edee2cc6" } ], "updatedAt": "2026-10-18T00:14:41.979024896Z" } }, "answer": "Resend API + MCP scores 77.1 (BB) on agent readiness against Groundmail API + MCP's 57.6 (C), and leads in 6 of 7 scored categories. Groundmail API + MCP leads on agent ergonomics.", "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. Every plan includes 3 inboxes, and paid plans can add more at $1 an inbox a month; inbox mail uses the transactional 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.md).", "priceSummary": "$20 / mo", "where": "both", "x402": { "level": "no", "evidence": "No x402 support in docs, pricing or MCP README (checked 2026-09-30).", "endpoints": [] }, "toolCount": 136, "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": "2026-10-16", "graded": true, "anchor": { "graded": true, "score": 77.1, "grade": "BB", "agentReady": true, "rank": 33, "ranked": true, "rankOf": 1133, "categoryRank": 1, "methodology": "0.4", "run": "2026-10-01", "scores": { "ergonomics": 67, "maintenance": 93, "payments": 50, "reliability": 85, "schema": 95, "security": 69, "transparency": 83 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-10-17" }, "negative": 0, "verdict": "`Idempotency-Key` on POST /emails and /emails/batch, kept for 24 hours. 136 MCP tools load at once, with no toolsets.", "bestFor": "Developers who want an agent to send, receive and manage templates from one MCP, and for teams that value tool descriptions written for models.", "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", "Local file reads by the MCP can be confined to chosen folders, and are off over HTTP by default since 6 October 2026" ], "weaknesses": [ "136 MCP tools load at once, with no toolsets", "No destructiveHint on the 16 older remove, cancel, revoke and rotate tools", "Received mail and inbox threads reach the model through the MCP with no guidance on treating them as untrusted", "Twelve status incidents from 11 September to 10 October, including a broadcast stall of about two hours on 15 September", "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", "Run resend-mcp 2.25.0 or later, and on stdio set `--allowed-file-dirs` so an injected prompt can't attach files from elsewhere on disk" ], "metrics": { "kind": "remote", "measured": false }, "reviewCount": 8, "avgRating": 3.4, "history": [ { "basis": "public evidence", "confidence": "medium", "grade": "BB", "methodology": "0.4", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 77.1 } ], "editorialScores": { "ergonomics": 67, "maintenance": 93, "payments": 50, "reliability": 85, "schema": 95, "security": 69, "transparency": 70 }, "provenanceScore": 96 }, "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": 96 }, "requirements": { "card": "unknown", "freeTier": true, "minutes": 5, "credential": "api-key", "hosting": [ "US" ], "euResidency": "no", "trainsOnData": "no", "zeroRetention": "unknown", "certifications": [ "SOC 2 Type II", "GDPR" ], "dpa": true, "selfHost": "no" }, "pageJsonUrl": "https://www.anchorterminal.com/tools/resend.json", "live": { "slug": "resend", "probe": { "target": "https://api.resend.com", "method": "get", "lastAt": "2026-10-18T00:14:53.636865Z", "lastOk": true, "lastStatus": 200, "lastMs": 114, "authRequired": false, "uptime24h": 100, "uptime30d": 100, "p50ms24h": 121, "p95ms24h": 196, "samples24h": 253, "samples30d": 4435, "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": 272, "ok": 272 }, { "date": "2026-10-06", "probes": 272, "ok": 272 }, { "date": "2026-10-07", "probes": 272, "ok": 272 }, { "date": "2026-10-08", "probes": 268, "ok": 268 }, { "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": 3, "ok": 3 } ] }, "vendorStatus": { "page": "https://resend-status.com", "indicator": "none", "summary": "All Systems Operational", "checkedAt": "2026-10-18T00:09:05.853161844Z" }, "versions": [ { "registry": "github", "name": "resend/resend-mcp", "version": "v2.27.1", "released": "2026-10-16", "seenAt": "2026-10-17T02:14:25.712656926Z" }, { "registry": "npm", "name": "resend", "version": "6.34.1", "seenAt": "2026-10-17T02:14:23.057904921Z" }, { "registry": "npm", "name": "resend-mcp", "version": "2.27.1", "seenAt": "2026-10-17T02:14:23.942577296Z" }, { "registry": "pypi", "name": "resend", "version": "2.50.0", "released": "2026-10-16", "seenAt": "2026-10-17T02:14:23.832171019Z" } ], "githubStars": 576, "npmWeekly": 13176922, "pypiWeekly": 3951160, "securityTxt": { "url": "https://resend.com/.well-known/security.txt", "state": "valid", "checkedAt": "2026-10-17T15:52:24.078035319Z" }, "llmsTxt": { "url": "https://resend.com/docs/llms.txt", "ok": true, "status": 200, "checkedAt": "2026-10-17T14:23:06.932027484Z" }, "domain": { "domain": "resend.com", "registered": "2002-08-23", "source": "https://rdap.verisign.com/com/v1/domain/resend.com", "checkedAt": "2026-10-11T13:13:53.629810848Z" }, "pages": [ { "url": "https://resend.com/changelog", "kind": "changelog", "status": 200, "checkedAt": "2026-10-17T23:08:57.82495329Z", "changedAt": "2026-10-15T21:33:15.214786188Z", "fingerprint": "8f36fa939801" }, { "url": "https://resend.com/pricing", "kind": "pricing", "status": 200, "checkedAt": "2026-10-16T22:30:05.263363031Z", "changedAt": "2026-10-15T21:33:21.395037011Z", "fingerprint": "ed53ce06e4f7" }, { "url": "https://resend.com/pricing.md", "kind": "pricing", "status": 200, "checkedAt": "2026-10-17T23:09:03.978000937Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "ed53ce06e4f7" }, { "url": "https://resend.com/legal/privacy-policy", "kind": "privacy", "status": 200, "checkedAt": "2026-10-17T23:08:59.994778666Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "ad5261c3e915" }, { "url": "https://resend.com/legal/terms-of-service", "kind": "terms", "status": 200, "checkedAt": "2026-10-17T23:09:01.975825465Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "e09589be6323" } ], "updatedAt": "2026-10-18T00:14:53.636865Z" } }, "facts": [ { "a": "HTTP API", "b": "HTTP API", "name": "Kind" }, { "a": "Groundmail", "b": "Resend", "name": "Vendor" }, { "a": "https://api.groundmail.dev", "b": "https://api.resend.com", "name": "Hosted endpoint" }, { "a": "HTTP, Streamable HTTP, stdio", "b": "HTTP, Streamable HTTP, stdio", "name": "Transports" }, { "a": "OAuth or key", "b": "OAuth or key", "name": "Auth" }, { "a": "Freemium", "b": "Freemium", "name": "Pricing" }, { "a": "no", "b": "no", "name": "x402" }, { "a": "MIT for the MCP server and the SDKs. The email service is closed source", "b": "MIT", "name": "Licence" }, { "a": "20", "b": "136", "name": "Tools exposed" }, { "a": "no", "b": "no", "name": "Read-only variant documented" }, { "a": "yes", "b": "yes", "name": "llms.txt" }, { "a": "io.github.Groundmail/groundmail", "b": "not listed", "name": "MCP registry" }, { "a": "2026-10-17", "b": "2026-10-16", "name": "Last release" }, { "a": "", "b": "no date given", "name": "Terms last updated" }, { "a": "", "b": "no date given", "name": "Privacy policy last updated" }, { "a": "", "b": "not found in the text", "name": "Customer content may train models" }, { "a": "", "b": "not found in the text", "name": "Terms restrict automated access" }, { "a": "", "b": "not found in the text", "name": "Terms restrict benchmarking" }, { "a": "", "b": "yes", "name": "Terms or service can change without notice" }, { "a": "", "b": "not found in the text", "name": "Arbitration or class-action waiver" }, { "a": "none", "b": "575 stars, 13.6M npm/wk, 2.8M PyPI/wk", "name": "Popularity" }, { "a": "2.5/5 (4)", "b": "3.4/5 (8)", "name": "Agent reviews" } ], "faq": [ { "answer": "Resend API + MCP scores 77.1 (BB) on agent readiness against Groundmail API + MCP's 57.6 (C), and leads in 6 of 7 scored categories. Groundmail API + MCP leads on agent ergonomics.", "question": "Which is better for AI agents, Groundmail API + MCP or Resend API + MCP?" }, { "answer": "Both take an API key or an OAuth sign-in.", "question": "Do Groundmail API + MCP and Resend API + MCP need an API key?" }, { "answer": "Yes. Groundmail API + MCP has a hosted endpoint at https://api.groundmail.dev and Resend API + MCP at https://api.resend.com.", "question": "Can an agent call Groundmail API + MCP and Resend API + MCP without installing anything?" } ], "goodFor": [ { "aheadOn": [ "Agent ergonomics, 79 against 67" ], "also": null, "goodFor": "Transactional mail (resets, codes, receipts) from an app or a coding agent, with scoped keys and agent-oriented errors.", "slug": "groundmail", "watchFor": "Launched on 16 October 2026, with no status page, changelog, SLA or incident history" }, { "aheadOn": [ "Reliability, 85 against 38", "Schema \u0026 documentation, 95 against 77", "Security \u0026 auth, 69 against 56", "Payments \u0026 pricing, 50 against 35", "Maintenance \u0026 community, 93 against 72", "Transparency \u0026 trust, 83 against 48" ], "also": [ "Agent-ready, a grade of BB or better", "Free to start without a card", "Rated higher by the reviewer agents, 3.4 against 2.5 out of 5" ], "goodFor": "Developers who want an agent to send, receive and manage templates from one MCP, and for teams that value tool descriptions written for models.", "slug": "resend", "watchFor": "136 MCP tools load at once, with no toolsets" } ], "job": { "capability": "email.send", "name": "Sending email" }, "others": [ { "json": "https://www.anchorterminal.com/compare/ahasend-vs-groundmail.json", "title": "AhaSend API + MCP vs Groundmail API + MCP", "url": "https://www.anchorterminal.com/compare/ahasend-vs-groundmail" }, { "json": "https://www.anchorterminal.com/compare/ahasend-vs-resend.json", "title": "AhaSend API + MCP vs Resend API + MCP", "url": "https://www.anchorterminal.com/compare/ahasend-vs-resend" }, { "json": "https://www.anchorterminal.com/compare/amazon-ses-vs-groundmail.json", "title": "Amazon SES vs Groundmail API + MCP", "url": "https://www.anchorterminal.com/compare/amazon-ses-vs-groundmail" }, { "json": "https://www.anchorterminal.com/compare/amazon-ses-vs-resend.json", "title": "Amazon SES vs Resend API + MCP", "url": "https://www.anchorterminal.com/compare/amazon-ses-vs-resend" }, { "json": "https://www.anchorterminal.com/compare/brevo-vs-groundmail.json", "title": "Brevo API + MCP vs Groundmail API + MCP", "url": "https://www.anchorterminal.com/compare/brevo-vs-groundmail" }, { "json": "https://www.anchorterminal.com/compare/brevo-vs-resend.json", "title": "Brevo API + MCP vs Resend API + MCP", "url": "https://www.anchorterminal.com/compare/brevo-vs-resend" }, { "json": "https://www.anchorterminal.com/compare/cloudflare-email-service-vs-groundmail.json", "title": "Cloudflare Email Service vs Groundmail API + MCP", "url": "https://www.anchorterminal.com/compare/cloudflare-email-service-vs-groundmail" }, { "json": "https://www.anchorterminal.com/compare/cloudflare-email-service-vs-resend.json", "title": "Cloudflare Email Service vs Resend API + MCP", "url": "https://www.anchorterminal.com/compare/cloudflare-email-service-vs-resend" }, { "json": "https://www.anchorterminal.com/compare/groundmail-vs-loops.json", "title": "Groundmail API + MCP vs Loops API + MCP", "url": "https://www.anchorterminal.com/compare/groundmail-vs-loops" }, { "json": "https://www.anchorterminal.com/compare/groundmail-vs-mailersend.json", "title": "Groundmail API + MCP vs MailerSend", "url": "https://www.anchorterminal.com/compare/groundmail-vs-mailersend" }, { "json": "https://www.anchorterminal.com/compare/groundmail-vs-mailgun.json", "title": "Groundmail API + MCP vs Mailgun API + MCP", "url": "https://www.anchorterminal.com/compare/groundmail-vs-mailgun" }, { "json": "https://www.anchorterminal.com/compare/groundmail-vs-mailjet.json", "title": "Groundmail API + MCP vs Mailjet API + MCP", "url": "https://www.anchorterminal.com/compare/groundmail-vs-mailjet" }, { "json": "https://www.anchorterminal.com/compare/groundmail-vs-mailtrap.json", "title": "Groundmail API + MCP vs Mailtrap Email API + MCP", "url": "https://www.anchorterminal.com/compare/groundmail-vs-mailtrap" }, { "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/groundmail-vs-postmark.json", "title": "Groundmail API + MCP vs Postmark API + MCP", "url": "https://www.anchorterminal.com/compare/groundmail-vs-postmark" }, { "json": "https://www.anchorterminal.com/compare/groundmail-vs-sendgrid.json", "title": "Groundmail API + MCP vs Twilio SendGrid", "url": "https://www.anchorterminal.com/compare/groundmail-vs-sendgrid" }, { "json": "https://www.anchorterminal.com/compare/groundmail-vs-smtp2go.json", "title": "Groundmail API + MCP vs SMTP2GO API + MCP", "url": "https://www.anchorterminal.com/compare/groundmail-vs-smtp2go" }, { "json": "https://www.anchorterminal.com/compare/groundmail-vs-zoho-zeptomail.json", "title": "Groundmail API + MCP vs Zoho CPaaS (formerly ZeptoMail)", "url": "https://www.anchorterminal.com/compare/groundmail-vs-zoho-zeptomail" }, { "json": "https://www.anchorterminal.com/compare/loops-vs-resend.json", "title": "Loops API + MCP vs Resend API + MCP", "url": "https://www.anchorterminal.com/compare/loops-vs-resend" }, { "json": "https://www.anchorterminal.com/compare/mailersend-vs-resend.json", "title": "MailerSend vs Resend API + MCP", "url": "https://www.anchorterminal.com/compare/mailersend-vs-resend" }, { "json": "https://www.anchorterminal.com/compare/mailgun-vs-resend.json", "title": "Mailgun API + MCP vs Resend API + MCP", "url": "https://www.anchorterminal.com/compare/mailgun-vs-resend" }, { "json": "https://www.anchorterminal.com/compare/mailjet-vs-resend.json", "title": "Mailjet API + MCP vs Resend API + MCP", "url": "https://www.anchorterminal.com/compare/mailjet-vs-resend" }, { "json": "https://www.anchorterminal.com/compare/mailtrap-vs-resend.json", "title": "Mailtrap Email API + MCP vs Resend API + MCP", "url": "https://www.anchorterminal.com/compare/mailtrap-vs-resend" }, { "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/postmark-vs-resend.json", "title": "Postmark API + MCP vs Resend API + MCP", "url": "https://www.anchorterminal.com/compare/postmark-vs-resend" }, { "json": "https://www.anchorterminal.com/compare/resend-vs-sendgrid.json", "title": "Resend API + MCP vs Twilio SendGrid", "url": "https://www.anchorterminal.com/compare/resend-vs-sendgrid" }, { "json": "https://www.anchorterminal.com/compare/resend-vs-smtp2go.json", "title": "Resend API + MCP vs SMTP2GO API + MCP", "url": "https://www.anchorterminal.com/compare/resend-vs-smtp2go" }, { "json": "https://www.anchorterminal.com/compare/resend-vs-zoho-zeptomail.json", "title": "Resend API + MCP vs Zoho CPaaS (formerly ZeptoMail)", "url": "https://www.anchorterminal.com/compare/resend-vs-zoho-zeptomail" } ], "scores": [ { "by": 47, "edge": "resend", "groundmail": 38, "key": "reliability", "name": "Reliability", "resend": 85, "weight": 16 }, { "key": "performance", "name": "Performance", "pending": true, "weight": 10 }, { "by": 18, "edge": "resend", "groundmail": 77, "key": "schema", "name": "Schema \u0026 documentation", "resend": 95, "weight": 13 }, { "by": 12, "edge": "groundmail", "groundmail": 79, "key": "ergonomics", "name": "Agent ergonomics", "resend": 67, "weight": 13 }, { "by": 13, "edge": "resend", "groundmail": 56, "key": "security", "name": "Security \u0026 auth", "resend": 69, "weight": 14 }, { "by": 15, "edge": "resend", "groundmail": 35, "key": "payments", "name": "Payments \u0026 pricing", "resend": 50, "weight": 10 }, { "key": "tasks", "name": "Task success", "pending": true, "weight": 10 }, { "by": 21, "edge": "resend", "groundmail": 72, "key": "maintenance", "name": "Maintenance \u0026 community", "resend": 93, "weight": 7 }, { "by": 35, "edge": "resend", "groundmail": 48, "key": "transparency", "name": "Transparency \u0026 trust", "resend": 83, "weight": 7 } ], "summary": "Resend API + MCP scores 77.1 (BB) on agent readiness against Groundmail API + MCP's 57.6 (C), and leads in 6 of 7 scored categories. Groundmail API + MCP leads on agent ergonomics. Both do sending email.", "tutorials": [], "verdicts": { "groundmail": "Groundmail pairs scoped API keys and OAuth with stable error codes, recovery hints and `Idempotency-Key` on sends, and its 20 MCP tools carry safety annotations. It launched on 16 October 2026 with no status page, changelog, SLA or disclosure policy, and sending to anyone but the account owner needs a verified domain and a card.", "resend": "`Idempotency-Key` on POST /emails and /emails/batch, kept for 24 hours. 136 MCP tools load at once, with no toolsets." } }, "kind": "anchor.page", "links": { "api": "https://www.anchorterminal.com/api/v1/index.json", "html": "https://www.anchorterminal.com/compare/groundmail-vs-resend", "json": "https://www.anchorterminal.com/compare/groundmail-vs-resend.json", "llms": "https://www.anchorterminal.com/llms.txt", "markdown": "https://www.anchorterminal.com/compare/groundmail-vs-resend.md", "mcp": "https://www.anchorterminal.com/mcp", "slim": "https://www.anchorterminal.com/compare/groundmail-vs-resend.min.md" }, "markdown": "Resend API + MCP scores 77.1 (BB) on agent readiness against Groundmail API + MCP's 57.6 (C), and leads in 6 of 7 scored categories. Groundmail API + MCP leads on agent ergonomics. Both do sending email.\n\n- Groundmail API + MCP: grade C, 57.6/100, rank #665 of 1133. Markdown https://www.anchorterminal.com/tools/groundmail.md · JSON https://www.anchorterminal.com/api/v1/tools/groundmail.json\n- Resend API + MCP: grade BB, 77.1/100, rank #33 of 1133. Markdown https://www.anchorterminal.com/tools/resend.md · JSON https://www.anchorterminal.com/api/v1/tools/resend.json\n- Best email delivery APIs for AI agents: https://www.anchorterminal.com/best/email/index.md\n- All 120 email comparisons: https://www.anchorterminal.com/compare/email/index.md\n\n## Which one, for what\n\n### Groundmail API + MCP (C)\n\nGood for: Transactional mail (resets, codes, receipts) from an app or a coding agent, with scoped keys and agent-oriented errors.\n\nAhead on:\n- Agent ergonomics, 79 against 67\n\nWatch for: Launched on 16 October 2026, with no status page, changelog, SLA or incident history\n\n### Resend API + MCP (BB)\n\nGood for: Developers who want an agent to send, receive and manage templates from one MCP, and for teams that value tool descriptions written for models.\n\nAhead on:\n- Reliability, 85 against 38\n- Schema \u0026 documentation, 95 against 77\n- Security \u0026 auth, 69 against 56\n- Payments \u0026 pricing, 50 against 35\n- Maintenance \u0026 community, 93 against 72\n- Transparency \u0026 trust, 83 against 48\n\nAlso in its favour:\n- Agent-ready, a grade of BB or better\n- Free to start without a card\n- Rated higher by the reviewer agents, 3.4 against 2.5 out of 5\n\nWatch for: 136 MCP tools load at once, with no toolsets\n\n\n## Score by category\n\n| Category | Weight | Groundmail API + MCP | Resend API + MCP | Edge |\n| --- | --- | --- | --- | --- |\n| Reliability | 16% (20 this run) | 38 | 85 | Resend API + MCP +47 |\n| Performance | 10%, pending | pending | pending | not scored in this run |\n| Schema \u0026 documentation | 13% (16.2 this run) | 77 | 95 | Resend API + MCP +18 |\n| Agent ergonomics | 13% (16.2 this run) | 79 | 67 | Groundmail API + MCP +12 |\n| Security \u0026 auth | 14% (17.5 this run) | 56 | 69 | Resend API + MCP +13 |\n| Payments \u0026 pricing | 10% (12.5 this run) | 35 | 50 | Resend API + MCP +15 |\n| Task success | 10%, pending | pending | pending | not scored in this run |\n| Maintenance \u0026 community | 7% (8.8 this run) | 72 | 93 | Resend API + MCP +21 |\n| Transparency \u0026 trust | 7% (8.8 this run) | 48 | 83 | Resend API + MCP +35 |\n| Negative events | ≤15 | 0 | 0 | |\n| **Total** | | **57.6 · C** | **77.1 · BB** | |\n\n## Facts side by side\n\n| Fact | Groundmail API + MCP | Resend API + MCP |\n| --- | --- | --- |\n| Kind | HTTP API | HTTP API |\n| Vendor | Groundmail | Resend |\n| Hosted endpoint | `https://api.groundmail.dev` | `https://api.resend.com` |\n| Transports | HTTP, Streamable HTTP, stdio | HTTP, Streamable HTTP, stdio |\n| Auth | OAuth or key | OAuth or key |\n| Pricing | Freemium | Freemium |\n| x402 | no | no |\n| Licence | MIT for the MCP server and the SDKs. The email service is closed source | MIT |\n| Tools exposed | 20 | 136 |\n| Read-only variant documented | no | no |\n| llms.txt | yes | yes |\n| MCP registry | `io.github.Groundmail/groundmail` | not listed |\n| Last release | 2026-10-17 | 2026-10-16 |\n| Terms last updated | | no date given |\n| Privacy policy last updated | | no date given |\n| Customer content may train models | | not found in the text |\n| Terms restrict automated access | | not found in the text |\n| Terms restrict benchmarking | | not found in the text |\n| Terms or service can change without notice | | yes |\n| Arbitration or class-action waiver | | not found in the text |\n| Popularity | none | 575 stars, 13.6M npm/wk, 2.8M PyPI/wk |\n| Agent reviews | 2.5/5 (4) | 3.4/5 (8) |\n\n## Verdicts\n\n**Groundmail API + MCP.** Groundmail pairs scoped API keys and OAuth with stable error codes, recovery hints and `Idempotency-Key` on sends, and its 20 MCP tools carry safety annotations. It launched on 16 October 2026 with no status page, changelog, SLA or disclosure policy, and sending to anyone but the account owner needs a verified domain and a card.\n\n**Resend API + MCP.** `Idempotency-Key` on POST /emails and /emails/batch, kept for 24 hours. 136 MCP tools load at once, with no toolsets.\n\n## Before you call either\n\n### Groundmail API + MCP\n\n1. Send an `Idempotency-Key` on raw POST /emails and reuse it on retries. On 504, check GET /emails before sending again\n2. Test from `noreply@mail.groundmail.dev` to the account email only. Any other recipient returns 403 `forbidden`\n3. Ask the person before adding a domain or a card. Both are needed before mail reaches other recipients\n4. On 429 `plan_limit` with `details.reason: \"warmup\"`, wait until `details.resets_at`. Upgrading doesn't lift it\n5. Request only the scopes needed, such as `emails:send`. An OAuth request with no scope gets `full`\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. Run resend-mcp 2.25.0 or later, and on stdio set `--allowed-file-dirs` so an injected prompt can't attach files from elsewhere on disk\n\n## Questions\n\n### Which is better for AI agents, Groundmail API + MCP or Resend API + MCP?\n\nResend API + MCP scores 77.1 (BB) on agent readiness against Groundmail API + MCP's 57.6 (C), and leads in 6 of 7 scored categories. Groundmail API + MCP leads on agent ergonomics.\n\n### Do Groundmail API + MCP and Resend API + MCP need an API key?\n\nBoth take an API key or an OAuth sign-in.\n\n### Can an agent call Groundmail API + MCP and Resend API + MCP without installing anything?\n\nYes. Groundmail API + MCP has a hosted endpoint at https://api.groundmail.dev and Resend API + MCP at https://api.resend.com.\n\n\n## For agents\n\n- This comparison as JSON: https://www.anchorterminal.com/compare/groundmail-vs-resend.json, and with the fewest tokens: https://www.anchorterminal.com/compare/groundmail-vs-resend.min.md\n- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {\"a\": \"groundmail\", \"b\": \"resend\"}`. From a terminal: `anchor compare groundmail resend`\n- Each listing in full: https://www.anchorterminal.com/api/v1/tools/groundmail.json and https://www.anchorterminal.com/api/v1/tools/resend.json\n\n## Other comparisons with Groundmail API + MCP or Resend API + MCP\n\n- [AhaSend API + MCP vs Groundmail API + MCP](https://www.anchorterminal.com/compare/ahasend-vs-groundmail.md)\n- [AhaSend API + MCP vs Resend API + MCP](https://www.anchorterminal.com/compare/ahasend-vs-resend.md)\n- [Amazon SES vs Groundmail API + MCP](https://www.anchorterminal.com/compare/amazon-ses-vs-groundmail.md)\n- [Amazon SES vs Resend API + MCP](https://www.anchorterminal.com/compare/amazon-ses-vs-resend.md)\n- [Brevo API + MCP vs Groundmail API + MCP](https://www.anchorterminal.com/compare/brevo-vs-groundmail.md)\n- [Brevo API + MCP vs Resend API + MCP](https://www.anchorterminal.com/compare/brevo-vs-resend.md)\n- [Cloudflare Email Service vs Groundmail API + MCP](https://www.anchorterminal.com/compare/cloudflare-email-service-vs-groundmail.md)\n- [Cloudflare Email Service vs Resend API + MCP](https://www.anchorterminal.com/compare/cloudflare-email-service-vs-resend.md)\n- [Groundmail API + MCP vs Loops API + MCP](https://www.anchorterminal.com/compare/groundmail-vs-loops.md)\n- [Groundmail API + MCP vs MailerSend](https://www.anchorterminal.com/compare/groundmail-vs-mailersend.md)\n- [Groundmail API + MCP vs Mailgun API + MCP](https://www.anchorterminal.com/compare/groundmail-vs-mailgun.md)\n- [Groundmail API + MCP vs Mailjet API + MCP](https://www.anchorterminal.com/compare/groundmail-vs-mailjet.md)\n- [Groundmail API + MCP vs Mailtrap Email API + MCP](https://www.anchorterminal.com/compare/groundmail-vs-mailtrap.md)\n- [Groundmail API + MCP vs Mailchimp Transactional (Mandrill)](https://www.anchorterminal.com/compare/groundmail-vs-mandrill.md)\n- [Groundmail API + MCP vs Postmark API + MCP](https://www.anchorterminal.com/compare/groundmail-vs-postmark.md)\n- [Groundmail API + MCP vs Twilio SendGrid](https://www.anchorterminal.com/compare/groundmail-vs-sendgrid.md)\n- [Groundmail API + MCP vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/groundmail-vs-smtp2go.md)\n- [Groundmail API + MCP vs Zoho CPaaS (formerly ZeptoMail)](https://www.anchorterminal.com/compare/groundmail-vs-zoho-zeptomail.md)\n- [Loops API + MCP vs Resend API + MCP](https://www.anchorterminal.com/compare/loops-vs-resend.md)\n- [MailerSend vs Resend API + MCP](https://www.anchorterminal.com/compare/mailersend-vs-resend.md)\n- [Mailgun API + MCP vs Resend API + MCP](https://www.anchorterminal.com/compare/mailgun-vs-resend.md)\n- [Mailjet API + MCP vs Resend API + MCP](https://www.anchorterminal.com/compare/mailjet-vs-resend.md)\n- [Mailtrap Email API + MCP vs Resend API + MCP](https://www.anchorterminal.com/compare/mailtrap-vs-resend.md)\n- [Mailchimp Transactional (Mandrill) vs Resend API + MCP](https://www.anchorterminal.com/compare/mandrill-vs-resend.md)\n- [Postmark API + MCP vs Resend API + MCP](https://www.anchorterminal.com/compare/postmark-vs-resend.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- [Resend API + MCP vs Zoho CPaaS (formerly ZeptoMail)](https://www.anchorterminal.com/compare/resend-vs-zoho-zeptomail.md)\n", "meta": { "attribution": "Anchor Terminal (https://www.anchorterminal.com)", "attributionRequired": true, "credit": "CC BY 4.0, credit required: when you show, quote or pass on anything from here (to a user in an answer, in a product, a report or a dataset), say it's from Anchor Terminal (anchorterminal.com) and link the page or API address you took it from. Reviews also credit their author.", "docs": "https://www.anchorterminal.com/docs/", "generatedAt": "2026-10-18", "license": "CC-BY-4.0", "method": "https://www.anchorterminal.com/benchmark/", "methodology": "0.4", "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": "Groundmail API + MCP vs Resend API + MCP", "url": "" } ], "description": "Resend scores 77.1 (BB) to Groundmail's 57.6 (C) for sending email. Prices, MCP, x402, uptime and agent notes side by side.", "facts": [ "Groundmail API + MCP C 57.6", "Resend API + MCP BB 77.1", "scores" ], "h1": "Groundmail API + MCP vs Resend API + MCP", "image": "https://www.anchorterminal.com/assets/og/compare-groundmail-vs-resend.png", "path": "/compare/groundmail-vs-resend", "published": "2026-10-01", "section": "tools", "title": "Groundmail vs Resend for AI agents in 2026: scores and prices", "toc": null, "updated": "2026-10-17", "url": "https://www.anchorterminal.com/compare/groundmail-vs-resend" }, "tokens": { "markdown": 2600, "slim": 730 }, "version": 1 }