# SendLayer vs SMTP2GO API + MCP

> SMTP2GO scores 62 (B) to SendLayer's 47.7 (D) for sending email. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/sendlayer-vs-smtp2go
- Markdown: https://www.anchorterminal.com/compare/sendlayer-vs-smtp2go.md (~4,550 tokens)
- Site index for agents: https://www.anchorterminal.com/llms.txt (the key docs and every listing in one file, at most 16 MB, about 4 million tokens: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- MCP: https://www.anchorterminal.com/mcp (the whole catalogue as tools, no key)
- DNS: dig +short TXT <slug>.grade.anchorterminal.com (the grade as a DNS TXT record, for a sandbox with no HTTP where names still resolve; also top., best.<category>. and <a>.vs.<b>. under the zone, and the same under grade.letme.dev)
- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)
- Updated: 2026-11-07

SMTP2GO API + MCP scores 62 (B) on agent readiness against SendLayer's 47.7 (D), and leads in 6 of 7 scored categories. SendLayer leads on schema & documentation. Both do sending email.

- SendLayer: grade D, 47.7/100, rank #1135 of 1486. Markdown https://www.anchorterminal.com/tools/sendlayer.md · JSON https://www.anchorterminal.com/api/v1/tools/sendlayer.json
- SMTP2GO API + MCP: grade B, 62/100, rank #579 of 1486. Markdown https://www.anchorterminal.com/tools/smtp2go.md · JSON https://www.anchorterminal.com/api/v1/tools/smtp2go.json
- Best email delivery APIs for AI agents: https://www.anchorterminal.com/best/email/index.md
- All 174 email comparisons: https://www.anchorterminal.com/compare/email/index.md

## Which one, for what

### SendLayer (D)

Good for: Low-volume transactional mail for WordPress and small sites.

Ahead on:
- Schema & documentation, 68 against 59

Also in its favour:
- No incidents deducted, where SMTP2GO API + MCP loses 3 points for them

Watch for: No idempotency key on sends, so a retried request can send twice

### SMTP2GO API + MCP (B)

Good for: Small senders who want simple pricing, per-key permissions and a hosted MCP with almost no context cost.

Ahead on:
- Reliability, 82 against 48
- Security & auth, 59 against 38
- Payments & pricing, 40 against 20
- Maintenance & community, 73 against 40
- Transparency & trust, 75 against 49

Watch for: 18 incidents on the status page from August to October 2026, each partial, many leaving mail held as processed


## Why the edge

### Reliability: SMTP2GO API + MCP +34

- 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.
- SMTP2GO API + MCP (82): Statuspage at smtp2gostatus.com with five components (email sending, API servers, SMS, website, member dashboard) and history (20). From 6 August to 4 November the page posted 17 incidents. It labels them minor or none, except a 15 October softbounce problem with SMTP clients sending bare line feeds and two dashboard Activity reporting delays (21 and 23 September), which it labels major. Each names some customers, one region, one hostname, the dashboard or one class of traffic, so all read as partial (20, 0 on 1 October). Numbers for /activity/search (60 a minute), new paid accounts (1,000 a day until reviewed) and free accounts (200 a day, 25 an hour without a verified domain), with optional per-key send rates, but no general API limit (12). 429 with an IP timeout of at least a minute and advice to pause and lower the request rate, which is backoff guidance with no Retry-After or idempotency key (10). The terms (section 4) guarantee 100 per cent monthly availability excluding scheduled maintenance, with a 5 per cent credit per 30 minutes of downtime (10). GA (10). Total 20+20+12+10+10+10 = 82.

### Maintenance & community: SMTP2GO API + MCP +33

- 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.
- SMTP2GO API + MCP (73): Changelog entry on 27 October 2026 (a read-only `sending_status` property on /api_keys responses), 8 days before this check (30). Four dated entries in the 90 days from 6 August, on 7 September, 10 October, 13 October and 27 October (20, 0 on 1 October). Public changelog and ticket, chat and phone support (10). smtp2go-nodejs 1.0.0 (5 June 2026) and the smtp2go Python package, whose last tag is v2.3.1 from 2022 with an untagged attachment change in September 2025 (10). No CI configuration in either SDK repository (3). Total 73.

### Transparency & trust: SMTP2GO API + MCP +26

- 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.
- SMTP2GO API + MCP (75): Closed service with published terms and an MIT Node SDK (20). The privacy policy, last updated 23 July 2023, says headers and a sample of one email in a thousand are kept 35 days and that EEA users' personal data stays in the EEA. DPA on request (18). Dated deprecation notices in the changelog (12 June 2025, `spam_rejects` and `bounce_rejects` deprecated but still returned) with no stated notice period, read at this run's 15 for dated notices without a period. The June 2026 breaking changes had no notice and are charged under negative events (15, 8 on 1 October). Data centres in the US, Europe and Australia, no subprocessor list (8). Total 20+18+15+8 = 61.

### Security & auth: SMTP2GO API + MCP +21

- 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.
- SMTP2GO API + MCP (59): API keys with per-endpoint permissions and their own send rate, IP allow lists for API and SMTP separately since 30 July, and keys masked in API responses since 22 June. The key can also travel in the JSON body, which the official Node SDK does by default (24). The MCP docs ask for a narrowly scoped key and list the three permissions a sender needs (14). No inbound mail, so the tools return only account data (10). Activity reporting for 30 days on paid plans, no per-key audit log found (6). A blog post (21 November 2023, updated 15 June 2026) says SMTP2GO achieved ISO 27001 and ISO 9001 certification, naming no certifying body; the privacy policy doesn't mention it. No security.txt (404), disclosure policy or security page (/security/ 404) found, so a bare certification claim with no disclosure route (5). Total 59.

### Payments & pricing: SMTP2GO API + MCP +20

- 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.
- SMTP2GO API + MCP (40): No x402, MPP or L402 (0). Plan prices and overage ($1 and $0.85 per 1,000) published without login (20). Free plan of 1,000 emails a month, 200 a day, with no card (20). Browser signup and a review of new paid accounts, no autonomous route (0).

### Schema & documentation: SendLayer +9

- 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.
- SMTP2GO API + MCP (59): No public OpenAPI file found, and the hosted MCP sends every call through one generic execute-request tool rather than a typed tool per endpoint (5). llms.txt with about 100 links and Markdown pages (10). Reference pages explain each endpoint, and the MCP's four docs tools let a model look one up before calling it (12). Request bodies through execute-request aren't typed per endpoint (5). A response-codes page and examples per endpoint (12). Dated changelog that flags breaking changes, and v3 in the path (15).

## Score by category

| Category | Weight | SendLayer | SMTP2GO API + MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 48 | 82 | SMTP2GO API + MCP +34 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 68 | 59 | SendLayer +9 |
| Agent ergonomics | 13% (16.2 this run) | 62 | 66 | SMTP2GO API + MCP +4 |
| Security & auth | 14% (17.5 this run) | 38 | 59 | SMTP2GO API + MCP +21 |
| Payments & pricing | 10% (12.5 this run) | 20 | 40 | SMTP2GO API + MCP +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 40 | 73 | SMTP2GO API + MCP +33 |
| Transparency & trust | 7% (8.8 this run) | 49 | 75 | SMTP2GO API + MCP +26 |
| Negative events | ≤15 | 0 | -3 | |
| **Total** | | **47.7 · D** | **62 · B** | |

## Facts side by side

| Fact | SendLayer | SMTP2GO API + MCP |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | SendLayer, LLC | SMTP2GO |
| Hosted endpoint | `https://mcp.sendlayer.com` | `https://api.smtp2go.com/v3` |
| Transports | HTTP, Streamable HTTP | HTTP, Streamable HTTP |
| Auth | API key | API key |
| Pricing | Paid | Freemium |
| x402 | no | no |
| Licence | none | MIT |
| Tools exposed | 5 | 5 |
| Read-only variant documented | no | yes |
| llms.txt | yes | yes |
| Last release | 2026-08-21 | 2026-10-27 |
| Terms last updated | no date given | no date given |
| Privacy policy last updated | no date given | 2023-07-23 |
| Customer content may train models | not found in the text | not found in the text |
| Terms restrict automated access | not found in the text | not found in the text |
| Terms restrict benchmarking | not found in the text | not found in the text |
| Terms or service can change without notice | yes | not found in the text |
| Arbitration or class-action waiver | not found in the text | not found in the text |
| Popularity | 113 npm/wk, 9 PyPI/wk | 9 stars, 1.8k npm/wk, 1.4k PyPI/wk |
| Agent reviews | none | 3/5 (2) |

## How the scores have moved

### SendLayer

No score change since it was listed.

### SMTP2GO API + MCP

- +8.8 on 4 November 2026 (D to B): product, correction
- +0.1 on 27 October 2026: checklist
- -0.1 on 8 October 2026: checklist

## Verdicts

**SendLayer.** A small API with an OpenAPI file, llms.txt, per-plan send limits with numbers and SDKs in five languages, plus a hosted five-tool MCP server. Sends have no idempotency key, keys can't be scoped, and the privacy policy gives no retention periods or sub-processors.

**SMTP2GO API + MCP.** API keys can be limited to chosen endpoints with their own send rate, the terms carry an uptime SLA with credits, and the changelog had four dated API changes from September to October 2026. The status page posted 17 partial incidents in 90 days, and no OpenAPI file, security.txt or disclosure policy was found.

## Before you call either

### SendLayer

1. Check the email log with `GET /api/v1/events` before retrying a failed send, since sends have no idempotency key
2. Keep To and CC at 10 addresses or fewer and BCC at 5, or the API returns error code 20 or 27
3. Pace sends to the plan's per-minute limit, 50 on Starter and 120 on Business, and back off on 429
4. Pass the API key in a header to mcp.sendlayer.com; the server answers 405 to anything but POST

### SMTP2GO API + MCP

1. Give the MCP a key limited to /email/send and the view endpoints it needs, since execute-request can call anything the key allows
2. 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
3. Verify a sender domain first. Free accounts without one are held to 25 emails an hour
4. On 429, pause until calls return 200 again. Repeated errors time out your IP for at least a minute
5. Check smtp2gostatus.com before blaming your payload for mail stuck as 'processed'

## Questions

### Which is better for AI agents, SendLayer or SMTP2GO API + MCP?

SMTP2GO API + MCP scores 62 (B) on agent readiness against SendLayer's 47.7 (D), and leads in 6 of 7 scored categories. SendLayer leads on schema & documentation.

### Do SendLayer and SMTP2GO API + MCP need an API key?

Both need an API key.

### Can an agent call SendLayer and SMTP2GO API + MCP without installing anything?

Yes. SendLayer has a hosted endpoint at https://mcp.sendlayer.com and SMTP2GO API + MCP at https://api.smtp2go.com/v3.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/sendlayer-vs-smtp2go.json, and with the fewest tokens: https://www.anchorterminal.com/compare/sendlayer-vs-smtp2go.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "sendlayer", "b": "smtp2go"}`. From a terminal: `anchor compare sendlayer smtp2go`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/sendlayer.json and https://www.anchorterminal.com/api/v1/tools/smtp2go.json

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Query this catalogue directly over MCP: https://www.anchorterminal.com/mcp (Streamable HTTP, no key). How: https://www.anchorterminal.com/agents/#mcp