# Mailjet API + MCP vs MailPace

> Mailjet scores 59.6 (C) 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/mailjet-vs-mailpace
- Markdown: https://www.anchorterminal.com/compare/mailjet-vs-mailpace.md (~4,600 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

Mailjet API + MCP scores 59.6 (C) on agent readiness against MailPace's 58.4 (C), and leads in 4 of 7 scored categories. MailPace leads on reliability and agent ergonomics. Both do sending email.

- Mailjet API + MCP: grade C, 59.6/100, rank #694 of 1510. Markdown https://www.anchorterminal.com/tools/mailjet.md · JSON https://www.anchorterminal.com/api/v1/tools/mailjet.json
- 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
- 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

### Mailjet API + MCP (C)

Good for: EU-based senders who want cheap transactional and marketing mail with data kept in the EU.

Ahead on:
- Schema & documentation, 76 against 54
- Payments & pricing, 30 against 25
- Maintenance & community, 79 against 65

Also in its favour:
- A hosted endpoint, with nothing to install
- Runs on your own machine
- Free to start without a card

Watch for: The MCP server registers 117 GET-only tools and can't send

### MailPace (C)

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

Ahead on:
- Reliability, 70 against 62
- Agent ergonomics, 71 against 53

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


## Why the edge

### Schema & documentation: Mailjet API + MCP +22

- Mailjet API + MCP (76): Published OpenAPI files, and the MCP server bundles a 528 KB copy (25). llms.txt with about 120 links and Markdown pages (10). MCP tool descriptions are the operation summary only, and the reference describes each resource without saying when not to use it (8). Typed from OpenAPI, with Limit, Offset, Sort and countOnly parameters across GET resources (11). Status-code and error-code pages, and examples per endpoint (12). Send API v3 and v3.1 are versioned, and the releases page has dated entries, but they're product launches rather than an API changelog (10). Re-read on 4 November, llms.txt lists the API reference, guides and a Deprecated Endpoints page; release entries on the releases page stop at 3 September.
- 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.

### Agent ergonomics: MailPace +18

- Mailjet API + MCP (53): The released MCP server registers one tool for each of the 117 GET paths in its bundled spec, with no toolsets (5). Limit, Offset, Sort and countOnly on list resources, with a maximum of 1,000 results a page (15). Documented status codes and error codes with messages (14). Every MCP tool is a GET, so nothing it does can change the account. The repository's 1.2.0 (29 October 2026, no tag) adds `readOnlyHint` and `destructiveHint` annotations, but npm couldn't be read, so its release is unconfirmed and not credited. The Send API has no idempotency key (6). Official SDKs for Node, Python and other languages, one POST /v3.1/send call carries a Messages array, and the MCP needs the key and secret joined as `key:secret` (13). 5 + 15 + 14 + 6 + 13 = 53.
- 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.

### Maintenance & community: Mailjet API + MCP +14

- Mailjet API + MCP (79): node-mailjet v7.1.1 on 26 October 2026, a code fix enforcing HTTPS-only requests, 9 days before the check (30). In the 90 days from 6 August, the releases page's 3 September entry and five SDK tags at half each (node-mailjet v7.1.0 on 14 August and v7.1.1, mailjet-apiv3-python 1.8.0 on 17 August, 1.9.0 on 14 September and 1.9.1 on 8 October), 3.5 in all (20). The MCP repository merges pull requests, and its README asks users to file an issue if npm and GitHub diverge. We couldn't see issue reply times (8). Node and Python SDKs released in the last 10 and 27 days (15). CI runs the tests, but the MCP repository's package.json says 1.2.0 while its git tags stop at v1.1.0-beta.1, and npm couldn't be read (6). 30 + 20 + 8 + 15 + 6 = 79.
- 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.

### Reliability: MailPace +8

- Mailjet API + MCP (62): Statuspage at mailjet.statuspage.io with history back to 2023, read through its history.atom feed (20). In the 90 days from 6 August the feed has two entries. A planned hour of infrastructure maintenance on 23 September, during which logins and API and SMTP sends were unavailable and submitted mail waited in the queue, and a Microsoft incident on 4 September that deferred mail to M365 only, with other providers unaffected. Both read as minor (20). The rate-limit page, unchanged on 4 November, says transactional endpoints have a high limit and others a 'much lower' one, with no numbers (0). A 429 on excess and advice to wait and retry, but no Retry-After header and no idempotency key for sends. SandboxMode validates a send without delivering (7). Enterprise plans list a 'Service Level Agreement' with no published terms, per the 1 October check, not re-read on 4 November (5). GA (10). 20 + 20 + 0 + 7 + 5 + 10 = 62.
- 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.

### Payments & pricing: Mailjet API + MCP +5

- Mailjet API + MCP (30): No x402, MPP or L402 (0). Plan prices are public, but the price per extra 1,000 emails sits behind a help-centre link rather than on the pricing page (10). Free plan of 6,000 emails a month, 200 a day, with no card (20). Browser signup, no autonomous route (0).
- 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.

## Score by category

| Category | Weight | Mailjet API + MCP | MailPace | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 62 | 70 | MailPace +8 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 76 | 54 | Mailjet API + MCP +22 |
| Agent ergonomics | 13% (16.2 this run) | 53 | 71 | MailPace +18 |
| Security & auth | 14% (17.5 this run) | 52 | 50 | Mailjet API + MCP +2 |
| Payments & pricing | 10% (12.5 this run) | 30 | 25 | Mailjet API + MCP +5 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 79 | 65 | Mailjet API + MCP +14 |
| Transparency & trust | 7% (8.8 this run) | 74 | 75 | MailPace +1 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **59.6 · C** | **58.4 · C** | |

## Facts side by side

| Fact | Mailjet API + MCP | MailPace |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Mailjet (Sinch) | OhMySMTP Ltd |
| Hosted endpoint | `https://api.mailjet.com/v3.1` | no (local only) |
| Transports | HTTP, stdio | HTTP |
| Auth | API key | API key |
| Pricing | Freemium | Paid |
| x402 | no | no |
| Licence | MIT | none |
| Tools exposed | 117 | 12 |
| Read-only variant documented | no | no |
| llms.txt | yes | no |
| Last release | 2026-10-26 | 2026-10-22 |
| Terms last updated | no date given | 2026-01-09 |
| Privacy policy last updated | 2026-09-29 | 2026-08-30 |
| Customer content may train models | not found in the text | not found in the text |
| Terms restrict automated access | not found in the text | yes |
| 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 | yes | not found in the text |
| Popularity | 255 stars, 177k npm/wk, 245k PyPI/wk | 1 stars, 207 npm/wk |
| Agent reviews | 2.5/5 (2) | none |

## How the scores have moved

### Mailjet API + MCP

- +0.1 on 4 November 2026: new evidence
- +0.1 on 27 October 2026: checklist
- -0.1 on 8 October 2026: checklist

### MailPace

No score change since it was listed.

## Verdicts

**Mailjet API + MCP.** SandboxMode on Send API v3.1 validates a payload without delivering it, and data is stored in the EU. The released MCP server registers 117 GET-only tools and can't send. Rate limits are published without numbers, and the 429 guidance is to wait and retry, with no Retry-After header or idempotency key.

**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.

## Before you call either

### Mailjet API + MCP

1. Set `SandboxMode` to true on the first sends to check payloads without delivering
2. Send with POST /v3.1/send and a `Messages` array, many messages per call
3. Use the MCP for statistics and contact lookups only, since it can't send
4. Pass `MAILJET_API_KEY` as `key:secret`. The server checks it at startup and exits if it's wrong
5. On 429, wait and retry. Non-transactional endpoints have much lower limits than send
6. Move legacy calls off `/v3/REST/newsletter` and the old statistics resources to `campaigndraft` and `statcounters`. They are deprecated and may be removed

### 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

## Questions

### Which is better for AI agents, Mailjet API + MCP or MailPace?

Mailjet API + MCP scores 59.6 (C) on agent readiness against MailPace's 58.4 (C), and leads in 4 of 7 scored categories. MailPace leads on reliability and agent ergonomics.

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

Both need an API key.

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

Mailjet API + MCP has a hosted endpoint at https://api.mailjet.com/v3.1. No hosted endpoint is listed for MailPace.


## For agents

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

## Other comparisons with Mailjet API + MCP or MailPace

- [AhaSend API + MCP vs Mailjet API + MCP](https://www.anchorterminal.com/compare/ahasend-vs-mailjet.md)
- [AhaSend API + MCP vs MailPace](https://www.anchorterminal.com/compare/ahasend-vs-mailpace.md)
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- [Cloudflare Email Service vs Mailjet API + MCP](https://www.anchorterminal.com/compare/cloudflare-email-service-vs-mailjet.md)
- [Cloudflare Email Service vs MailPace](https://www.anchorterminal.com/compare/cloudflare-email-service-vs-mailpace.md)
- [Groundmail API + MCP vs Mailjet API + MCP](https://www.anchorterminal.com/compare/groundmail-vs-mailjet.md)
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- [Loops API + MCP vs Mailjet API + MCP](https://www.anchorterminal.com/compare/loops-vs-mailjet.md)
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- [MailerSend vs Mailjet API + MCP](https://www.anchorterminal.com/compare/mailersend-vs-mailjet.md)
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- [Mailjet API + MCP vs Mailtrap Email API + MCP](https://www.anchorterminal.com/compare/mailjet-vs-mailtrap.md)
- [Mailjet API + MCP vs Mailchimp Transactional (Mandrill)](https://www.anchorterminal.com/compare/mailjet-vs-mandrill.md)
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- [Mailjet API + MCP vs SendLayer](https://www.anchorterminal.com/compare/mailjet-vs-sendlayer.md)
- [Mailjet API + MCP vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/mailjet-vs-smtp2go.md)
- [Mailjet API + MCP vs Zoho CPaaS (formerly ZeptoMail)](https://www.anchorterminal.com/compare/mailjet-vs-zoho-zeptomail.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 SMTP2GO API + MCP](https://www.anchorterminal.com/compare/mailpace-vs-smtp2go.md)
- [MailPace vs Zoho CPaaS (formerly ZeptoMail)](https://www.anchorterminal.com/compare/mailpace-vs-zoho-zeptomail.md)

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