# MailPace vs SMTP2GO API + MCP

> SMTP2GO scores 62 (B) to MailPace's 58.4 (C) for sending email. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/mailpace-vs-smtp2go
- Markdown: https://www.anchorterminal.com/compare/mailpace-vs-smtp2go.md (~4,950 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 MailPace's 58.4 (C), and leads in 5 of 7 scored categories. MailPace leads on agent ergonomics. Both do sending email.

- MailPace: grade C, 58.4/100, rank #754 of 1510. Markdown https://www.anchorterminal.com/tools/mailpace.md · JSON https://www.anchorterminal.com/api/v1/tools/mailpace.json
- SMTP2GO API + MCP: grade B, 62/100, rank #581 of 1510. 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

### MailPace (C)

Good for: Low-volume transactional mail from EU-hosted infrastructure with idempotent sends and no tracking.

Ahead on:
- Agent ergonomics, 71 against 66

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

Watch for: No OpenAPI spec, llms.txt or Markdown docs for agents; the reference is Docusaurus pages

### 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 70
- Schema & documentation, 59 against 54
- Security & auth, 59 against 50
- Payments & pricing, 40 against 25
- Maintenance & community, 73 against 65

Also in its favour:
- A hosted endpoint, with nothing to install

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


## Why the edge

### Payments & pricing: SMTP2GO API + MCP +15

- MailPace (25): No x402, MPP or L402 (0). $10 a month for 10,000 emails and $1 per 1,000 after, loaded from Paddle on the pricing page and stated in the comparison pages' tables without login (20). A free plan of up to 100 emails a month is available only by emailing support, so it isn't self-serve (5 of 20). Signup, DKIM verification and payment happen in a browser (0). Total 25.
- 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).

### Reliability: SMTP2GO API + MCP +12

- MailPace (70): Graded with the hosted lines. A public Upptime status page at status.mailpace.com, driven by the mailpace/status repository, with monitors for the application, SMTP, docs, blog and landing page and GitHub issues as incident reports (20). The 90 days from 8 August hold two incidents, an application outage on 22 September 2026 that the operator put down to an upstream provider returning 5xx (issue open for two minutes), and SMTP down on 2 November 2026 for about 35 minutes, which leaves SMTP at 99.65% for the week. Minor incidents only (20). No rate limit numbers are published; the docs say limits vary by organisation age, plan and history (0). A documented 429 with its message, no Retry-After or backoff guidance, and an `Idempotency-Key` on sends with written retry rules (10 of 15). The terms guarantee 99% monthly availability of the API and dashboard with a 5% credit per 30 minutes (10). The API is at v1 with no beta label (10). Total 70.
- 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.

### Security & auth: SMTP2GO API + MCP +9

- MailPace (50): Per-domain server tokens that can only send from and read status for their domain, and an organisation token that creates, renames and revokes domain tokens through the Domains API. Tokens travel in headers only. The authentication page still tells users to contact support to regenerate a leaked token (25 of 30). No read-only token. A domain token can't touch other domains, and the unpublished MCP server has an optional recipient allowlist. No approval step on the hosted API (8 of 20). Inbound mail reaches the customer's webhook as untrusted content, and Email Status returns bounce text. The MCP README warns about prompt injection and suggests the allowlist (9 of 15). The dashboard keeps sent mail for 30 days; no log of API calls was found (6 of 15). No security.txt (404 on mailpace.com and app.mailpace.com), no disclosure policy, bug bounty, SOC 2 or ISO 27001. WebAuthn-only two-factor sign-in and Ed25519-signed webhooks are documented (2 of 20). Total 50.
- 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.

### Maintenance & community: SMTP2GO API + MCP +8

- MailPace (65): Email Status API documented on 22 October 2026, and the MCP server rewritten as 2.0.0 on 4 November 2026, two days before this check (30). In the 90 days from 8 August, the Q3 changelog post of 31 August, the Email Status docs of 22 October, a mailpace-rails push on 17 October and the MCP rewrite, but only one changelog post (15 of 20). A closed service with email support. Three pull requests to the MCP repository from 2025 have no reply (8 of 15). Not in the official MCP registry (search for mailpace returned nothing on 6 November). The Node library was last pushed in October 2024 and Go in January 2024, while mailpace-rails is current (7 of 15). The MCP server gained CI with tests on 4 November; the older SDKs weren't checked for CI (5 of 10). Total 65.
- 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.

### Schema & documentation: SMTP2GO API + MCP +5

- MailPace (54): No OpenAPI or other machine-readable contract for the HTTPS API. The MCP server's 12 tools have typed zod inputs and output schemas, but that server isn't published yet, so partial credit (8 of 25). llms.txt answers 404 on mailpace.com and docs.mailpace.com, and no Markdown copies are served (0). The reference states what each endpoint does, and the introduction says when not to use it (transactional only, no batch, no static IPs) (12 of 20). Field tables give type, examples and required or optional, with enums for status, sort and direction and the 50-recipient cap in text (9 of 15). Examples in curl and six languages and a full table of error responses with messages, though several listed messages have a broken quote (`{"error:"...`) and the send reference says 30 MB where the home page says 25 MB (12 of 15). Version in the path with a promise that an old version runs until a published end-of-life date, and dated changelog posts (13 of 15). Total 54.
- 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).

### Agent ergonomics: MailPace +5

- MailPace (71): Responses are small, the send returns an id and status and Email Status returns one email (18 of 25). Only the domains list takes `limit`, `offset`, `sort` and `direction`; there is no endpoint to list or search sent mail (8 of 20). Errors are JSON with a human message and an HTTP status for each case in the documented table, with no stable error codes (14 of 20). `Idempotency-Key` on sends, kept 24 hours per token, and failed validations are not stored so they can be retried. The MCP server marks send as not idempotent and revoke as destructive (18 of 20). A send needs from, to, a subject and a body; official libraries for Node, Rails, Go and PHP transports and an SMTP route (13 of 15). Total 71.
- SMTP2GO API + MCP (66): Five tools, four of them read-only docs lookups (25). We didn't check pagination or output limits on /activity/search beyond its 60-a-minute limit (8). Documented response codes with messages (14). The docs tools only read. execute-request can send or delete with nothing marking it so that we found, and there's no idempotency key (6). Node and Python SDKs, and a send needs only sender, to, subject and a body (13).

## Score by category

| Category | Weight | MailPace | SMTP2GO API + MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 70 | 82 | SMTP2GO API + MCP +12 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 54 | 59 | SMTP2GO API + MCP +5 |
| Agent ergonomics | 13% (16.2 this run) | 71 | 66 | MailPace +5 |
| Security & auth | 14% (17.5 this run) | 50 | 59 | SMTP2GO API + MCP +9 |
| Payments & pricing | 10% (12.5 this run) | 25 | 40 | SMTP2GO API + MCP +15 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 65 | 73 | SMTP2GO API + MCP +8 |
| Transparency & trust | 7% (8.8 this run) | 75 | 75 | even |
| Negative events | ≤15 | 0 | -3 | |
| **Total** | | **58.4 · C** | **62 · B** | |

## Facts side by side

| Fact | MailPace | SMTP2GO API + MCP |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | OhMySMTP Ltd | SMTP2GO |
| Hosted endpoint | no (local only) | `https://api.smtp2go.com/v3` |
| Transports | HTTP | HTTP, Streamable HTTP |
| Auth | API key | API key |
| Pricing | Paid | Freemium |
| x402 | no | no |
| Licence | none | MIT |
| Tools exposed | 12 | 5 |
| Read-only variant documented | no | yes |
| llms.txt | no | yes |
| Last release | 2026-10-22 | 2026-10-27 |
| Terms last updated | 2026-01-09 | no date given |
| Privacy policy last updated | 2026-08-30 | 2023-07-23 |
| Customer content may train models | not found in the text | not found in the text |
| Terms restrict automated access | yes | 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 | not found in the text | not found in the text |
| Arbitration or class-action waiver | not found in the text | not found in the text |
| Popularity | 1 stars, 207 npm/wk | 9 stars, 1.8k npm/wk, 1.4k PyPI/wk |
| Agent reviews | none | 3/5 (2) |

## How the scores have moved

### MailPace

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

**MailPace.** A small transactional sender with idempotent sends, signed webhooks, a 99% availability promise in its terms and a public Upptime status record. There is no OpenAPI spec, no published rate limit, no llms.txt, and its MCP server was rewritten on 4 November 2026 but isn't on npm or in the MCP registry yet.

**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

### MailPace

1. Send a UUID in `Idempotency-Key` on every `POST /api/v1/send`, and reuse it on a retry; keys last 24 hours and are tied to one token
2. Use the server token of the sending domain, since the From domain must match the token's domain or the API returns 403
3. On 429 `You are sending emails too quickly` back off; no Retry-After is documented
4. Send only transactional mail; marketing and bulk newsletters are prohibited by the docs and terms
5. Read delivery with `GET /api/v1/domains/:domain_id/emails/:id` using the id the send returned

### 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, MailPace or SMTP2GO API + MCP?

SMTP2GO API + MCP scores 62 (B) on agent readiness against MailPace's 58.4 (C), and leads in 5 of 7 scored categories. MailPace leads on agent ergonomics.

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

Both need an API key.

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

No hosted endpoint is listed for MailPace. SMTP2GO API + MCP has a hosted endpoint at https://api.smtp2go.com/v3.


## For agents

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

## Other comparisons with MailPace or SMTP2GO API + MCP

- [AhaSend API + MCP vs MailPace](https://www.anchorterminal.com/compare/ahasend-vs-mailpace.md)
- [AhaSend API + MCP vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/ahasend-vs-smtp2go.md)
- [Amazon SES vs MailPace](https://www.anchorterminal.com/compare/amazon-ses-vs-mailpace.md)
- [Amazon SES vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/amazon-ses-vs-smtp2go.md)
- [Brevo API + MCP vs MailPace](https://www.anchorterminal.com/compare/brevo-vs-mailpace.md)
- [Brevo API + MCP vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/brevo-vs-smtp2go.md)
- [Cloudflare Email Service vs MailPace](https://www.anchorterminal.com/compare/cloudflare-email-service-vs-mailpace.md)
- [Cloudflare Email Service vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/cloudflare-email-service-vs-smtp2go.md)
- [Groundmail API + MCP vs MailPace](https://www.anchorterminal.com/compare/groundmail-vs-mailpace.md)
- [Groundmail API + MCP vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/groundmail-vs-smtp2go.md)
- [Loops API + MCP vs MailPace](https://www.anchorterminal.com/compare/loops-vs-mailpace.md)
- [Loops API + MCP vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/loops-vs-smtp2go.md)
- [MailerSend vs MailPace](https://www.anchorterminal.com/compare/mailersend-vs-mailpace.md)
- [MailerSend vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/mailersend-vs-smtp2go.md)
- [Mailgun API + MCP vs MailPace](https://www.anchorterminal.com/compare/mailgun-vs-mailpace.md)
- [Mailgun API + MCP vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/mailgun-vs-smtp2go.md)
- [Mailjet API + MCP vs MailPace](https://www.anchorterminal.com/compare/mailjet-vs-mailpace.md)
- [Mailjet API + MCP vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/mailjet-vs-smtp2go.md)
- [MailPace vs Mailtrap Email API + MCP](https://www.anchorterminal.com/compare/mailpace-vs-mailtrap.md)
- [MailPace vs Mailchimp Transactional (Mandrill)](https://www.anchorterminal.com/compare/mailpace-vs-mandrill.md)
- [MailPace vs Postmark API + MCP](https://www.anchorterminal.com/compare/mailpace-vs-postmark.md)
- [MailPace vs Resend API + MCP](https://www.anchorterminal.com/compare/mailpace-vs-resend.md)
- [MailPace vs Twilio SendGrid](https://www.anchorterminal.com/compare/mailpace-vs-sendgrid.md)
- [MailPace vs SendLayer](https://www.anchorterminal.com/compare/mailpace-vs-sendlayer.md)
- [MailPace vs Zoho CPaaS (formerly ZeptoMail)](https://www.anchorterminal.com/compare/mailpace-vs-zoho-zeptomail.md)
- [Mailtrap Email API + MCP vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/mailtrap-vs-smtp2go.md)
- [Mailchimp Transactional (Mandrill) vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/mandrill-vs-smtp2go.md)
- [Postmark API + MCP vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/postmark-vs-smtp2go.md)
- [Resend API + MCP vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/resend-vs-smtp2go.md)
- [Twilio SendGrid vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/sendgrid-vs-smtp2go.md)
- [SendLayer vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/sendlayer-vs-smtp2go.md)
- [SMTP2GO API + MCP vs Zoho CPaaS (formerly ZeptoMail)](https://www.anchorterminal.com/compare/smtp2go-vs-zoho-zeptomail.md)

---

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