# Groundmail API + MCP vs SendLayer (slim)

> Groundmail scores 64.5 (B) to SendLayer's 47.7 (D) for sending email. Prices, MCP, x402, uptime and agent notes side by side.

- Full: https://www.anchorterminal.com/compare/groundmail-vs-sendlayer.md (~5,200 tokens) · this version ~3,080 tokens · JSON https://www.anchorterminal.com/compare/groundmail-vs-sendlayer.json · canonical https://www.anchorterminal.com/compare/groundmail-vs-sendlayer
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · MCP: https://www.anchorterminal.com/mcp · Updated: 2026-11-07
- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)

Groundmail API + MCP scores 64.5 (B) on agent readiness against SendLayer's 47.7 (D), and leads in every scored category. Both do sending email.

- Groundmail API + MCP: B 64.5, rank #460 of 1486 · https://www.anchorterminal.com/tools/groundmail.min.md
- SendLayer: D 47.7, rank #1135 of 1486 · https://www.anchorterminal.com/tools/sendlayer.min.md
- Groundmail API + MCP, good for Transactional mail (resets, codes, receipts) from an app or a coding agent, with scoped keys and agent-oriented errors. Ahead on Reliability, 68 against 48; Schema & documentation, 88 against 68; Agent ergonomics, 69 against 62; Security & auth, 63 against 38; Payments & pricing, 35 against 20; Maintenance & community, 77 against 40; Transparency & trust, 71 against 49. Also Runs on your own machine.
- SendLayer, good for Low-volume transactional mail for WordPress and small sites. Also No incidents deducted, where Groundmail API + MCP loses 3 points for them.

| Category | Groundmail API + MCP | SendLayer |
| --- | --- | --- |
| Reliability (16%) | 68 | 48 |
| Performance (10%) | pending | pending |
| Schema & documentation (13%) | 88 | 68 |
| Agent ergonomics (13%) | 69 | 62 |
| Security & auth (14%) | 63 | 38 |
| Payments & pricing (10%) | 35 | 20 |
| Task success (10%) | pending | pending |
| Maintenance & community (7%) | 77 | 40 |
| Transparency & trust (7%) | 71 | 49 |

| Fact (where they differ) | Groundmail API + MCP | SendLayer |
| --- | --- | --- |
| Vendor | Groundmail | SendLayer, LLC |
| Hosted endpoint | `https://api.groundmail.dev` | `https://mcp.sendlayer.com` |
| Transports | HTTP, Streamable HTTP, stdio | HTTP, Streamable HTTP |
| Auth | OAuth or key | API key |
| Pricing | Freemium | Paid |
| Licence | MIT for the MCP server and the SDKs. The email service is closed source | none |
| Tools exposed | 20 | 5 |
| MCP registry | `io.github.Groundmail/groundmail` | not listed |
| Last release | 2026-11-04 | 2026-08-21 |
| Terms last updated | 2026-10-29 | no date given |
| Privacy policy last updated | 2026-10-29 | no date given |
| Terms or service can change without notice | not found in the text | yes |
| Popularity | none | 113 npm/wk, 9 PyPI/wk |
| Agent reviews | 2.5/5 (4) | none |

Why the edge:
- Maintenance & community, Groundmail API + MCP +37: Groundmail API + MCP 77 (groundmail-mcp 0.27.0, published to the official MCP registry on 4 November 2026 (30). The official MCP registry lists 42 groundmail-mcp versions published from 18 October to 4 November on the first page of its listing, the Go SDK is tagged to go/v0.9.2 (23 October), and the changelog has 155 dated entries, 136 of them since 16 October (20). The public GitHub repositories are mirrors with no readable issue replies, and support is by email and in-product chat whose replies weren't read; the public changelog is new since 17 October (8 of 25, judgement call). In the official MCP registry under the GitHub-verified namespace io.github.Groundmail, with current SDKs (15). Tests in the MCP and SDK repositories and a current MCP SDK dependency (^1.32.2), but no CI workflow in the public repositories (4 of 10). 30+20+8+15+4 = 77.); SendLayer 40 (The Node and Python SDKs were last released as 1.1.0 on 21 August 2026, 77 days before this check (20). One SDK release in the 90 days and no dated changelog (0 of 20). A closed service with a support form and docs updated through 2026, but no public changelog (5 of 15). Not in the official MCP registry (search for sendlayer returned nothing on 6 November). Official SDKs in five languages (10 of 15). The SDK repositories exist on GitHub under sendlayer; their CI wasn't read (5 of 10). Total 40.)
- Security & auth, Groundmail API + MCP +25: Groundmail API + MCP 63 (Scoped API keys with Full, Send only, Read only and custom sets, send keys limited to named domains, and OAuth with PKCE S256, resource indicators, one-hour tokens and refresh-token reuse detection. Bearer tokens go in the header only. An OAuth request that names no scope gets `full` (28 of 30). Read-only and send-only presets for keys and MCP connections, and the sandbox limits sends to the account email until a domain and card are on file. Confirmation before a send is left to the client (16 of 20). The MCP returns subjects and bounce reasons, and the API returns full inbound messages from /received-emails. No prompt-injection guidance in the MCP source or README (4 of 15). Connected CLIs and agents are listed with their scopes and can be revoked, keys show `last_used_at`, GET /emails logs each send, and since 3 November a webhook delivery log shows every attempt. No request or audit log is documented (8 of 15). groundmail.dev now serves a security.txt (contact support@groundmail.dev, expires 20 October 2027) with no acknowledgement time, no disclosure policy, bug bounty or certification found; graded as mails-ai and tokenrip (7 of 20). 28+16+4+8+7 = 63.); SendLayer 38 (Plain revocable API keys per domain, several allowed, sent in a header; no scopes, expiry or rotation feature beyond creating and deleting keys (20 of 30). No read-only key or approval step (0 of 20). The API returns event data, not received mail (10 of 15). Email logs kept 3, 15 or 30 days by plan, and no log of API calls was found (8 of 15). No security.txt (404), disclosure policy, bug bounty or certification found (0 of 20). Total 38.)
- Transparency & trust, Groundmail API + MCP +22: Groundmail API + MCP 71 (Closed service with published terms (updated 3 November 2026), and the MCP server and SDKs under MIT (20 of 30). Since 22 October retention is published per plan (7 days on Free, 30 on Pro, 90 on Scale and pay as you go, up to a year on Dedicated), and since 3 November a DPA with the EU Standard Contractual Clauses and a 48-hour incident notice and a public subprocessor list are published. The privacy policy still says message logs are kept 'according to plan and configuration' and that customer data is processed 'in the United States and other regions' (20 of 30). No deprecation policy. The terms promise notice of material changes by email or in the product, the errors page says existing codes keep their meaning, and the changelog dates each change, but 3 November's send checks took effect the day they were posted (3 of 20). The subprocessor list names Google Cloud, OVHcloud and Cloudflare with what each processes and where (United States, Cloudflare's global network), with 30 days' notice before a new one; the privacy policy's 'other regions' leaves the rest open (16 of 20, judgement call). 20+20+3+16 = 59.); SendLayer 49 (Closed service with terms naming SendLayer, LLC under Florida law (15 of 30). The privacy policy is undated, says data is kept as long as the account is active or as needed, and names no retention periods, DPA or processors; only the pricing page gives log retention per plan (8 of 30). No deprecation policy or dated notices (0). No sub-processors or data locations disclosed (0). Total 23.)
- Reliability, Groundmail API + MCP +20: Groundmail API + MCP 68 (Read with the hosted lines, for the API and hosted MCP an agent calls. A public status page at status.groundmail.dev since 19 October 2026, with nine components (REST API, SMTP relay, mail delivery, webhooks, inbound, tracking, dashboard, docs, MCP server), per-minute outside checks and 90-day bars (20). Its history starts on 20 October, and its RSS feed and page show no incident posted since, so the record is short (15). Sending quotas are published with numbers (3,000 a month and 100 a day on Free, and a new-account limit from 1,000 product and 3,000 transactional recipients a day that doubles with clean sending), but the short-window limit behind `rate_limited` has no published number (8 of 15, docs per the 17 October check). `Retry-After` on 429, a backoff recipe of up to five tries, and `Idempotency-Key` on POST /emails and /events kept 24 hours, and since 2 November on POST /emails/batch (15). No SLA, and the terms disclaim uninterrupted availability (0). Not labelled beta or preview, apart from the provider importer and the Zapier app (10). 20+15+8+15+0+10 = 68.); SendLayer 48 (Graded with the hosted lines. A Cronitor status page at status.sendlayer.com with components for the app, SMTP, tracking links, the website and each plan's sending IPs, and a history (15 of 20, see below). The 90 days from 8 August hold 98 automated outage entries, 13 of them on SendLayer Services Health, most on per-plan IP monitors, all marked resolved but with no durations or write-ups, so their size can't be judged (5 of 30). Send limits per minute, hour and day are published per plan, plus recipient and size caps (15). 429 appears in the error code list, with no Retry-After, backoff guidance or idempotency for sends (3 of 15). No SLA found (0). The API is at v1 with no beta label (10). The status page's uptime columns showed no data on 6 November, so the component line takes 15 of 20 rather than 20. Total 48.)
- Schema & documentation, Groundmail API + MCP +20: Groundmail API + MCP 88 (OpenAPI 3.1 at docs.groundmail.dev/openapi.yaml with 70 operations, each naming its scope in `x-required-scope`, and typed input and output schemas on every MCP tool (25, OpenAPI per the 17 October check; a permission check refused the request on 4 November). llms.txt, llms-full.txt, Agent Skills and, since 22 October, a Markdown version of every docs page (10). MCP descriptions run from one line to a paragraph, with a few 'do not combine' rules, and only 21 of 70 OpenAPI operations carried a description on 17 October (12 of 20). The OpenAPI document bounds `limit` from 1 to 100 and uses enums, but the MCP `limit` is an unbounded number and template `variables` are free-form (11 of 15). An errors page with every code, its status, a fix and examples, 69 of 70 operations listing 4xx responses, and curl and SDK examples (15). A public changelog at groundmail.dev/changelog with 155 dated entries from 24 July to 3 November 2026 and an RSS feed, semver tags on the MCP server and Go SDK, and a versioned OpenAPI document (15). 25+10+12+11+15+15 = 88.); SendLayer 68 (OpenAPI file at developers.sendlayer.com/api-reference/sendlayer.json (version 1.0.1) covering four paths, send, events and webhooks (25). llms.txt and Markdown copies of every developer page (10). Operation summaries say what each call does; nothing says when not to use one, and the hosted MCP server's tool definitions aren't public (10 of 20). Parameters are typed but without enums or limits, and the event filter is a free string (7 of 15). Code samples in five languages and a table of 35 error codes, but the spec documents only 200 responses (11 of 15). Version in the path and in the spec, with no public changelog (5 of 15). Total 68.)
- Payments & pricing, Groundmail API + MCP +15: Groundmail API + MCP 35 (No x402, MPP or L402 in the docs, the changelog or the pricing page (0). Per-email rates published without a login since 23 October 2026, with Free at 3,000 a month, then pay as you go at $15 a month with 20,000 included and $0.70, $0.50 and $0.30 per 1,000 by band (20). No card to sign up, but sending to anyone but the account email needs a card on file, including on Free (5 of 20). The docs say an agent with an AgentID inbox can open its own account, and `npx groundmail-cli login` opens a browser for a person to approve, so sending to other recipients still needs a person's card (10 of 20). 0+20+5+10 = 35.); SendLayer 20 (No x402, MPP or L402 (0). Plan prices are public but only as annual plans, with no per-email overage price; accounts are upgraded automatically at the limit (10 of 20). A free trial of 200 emails is offered through checkout; whether it needs a card couldn't be read, since robots.txt disallows the add-to-cart URLs (10 of 20). A person signs up and authorises a domain in a browser (0). Total 20.)