# Mailjet API + MCP vs SMTP2GO API + MCP

> Mailjet API + MCP has a score of 59.5 (C) against SMTP2GO API + MCP's 53.2 (D). Both do email send. The largest gap is maintenance & community, 26 points. Category scores, facts, verdicts and agent notes side by side.

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- Updated: 2026-10-04

Mailjet API + MCP has a score of 59.5 (C) against SMTP2GO API + MCP's 53.2 (D). Both do email send. The largest gap is maintenance & community, 26 points.

- Mailjet API + MCP: grade C, 59.5/100, rank #264 of 452. Markdown https://www.anchorterminal.com/tools/mailjet.md · JSON https://www.anchorterminal.com/api/v1/tools/mailjet.json
- SMTP2GO API + MCP: grade D, 53.2/100, rank #336 of 452. Markdown https://www.anchorterminal.com/tools/smtp2go.md · JSON https://www.anchorterminal.com/api/v1/tools/smtp2go.json

## Which one, for what

Pick Mailjet API + MCP for reliability (+15), schema & documentation (+17), maintenance & community (+26).

Pick SMTP2GO API + MCP for agent ergonomics (+13), security & auth (+8), payments & pricing (+10).

## Score by category

| Category | Weight | Mailjet API + MCP | SMTP2GO API + MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 62 | 47 | Mailjet API + MCP +15 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 76 | 59 | Mailjet API + MCP +17 |
| Agent ergonomics | 13% (16.2 this run) | 53 | 66 | SMTP2GO API + MCP +13 |
| Security & auth | 14% (17.5 this run) | 52 | 60 | SMTP2GO API + MCP +8 |
| Payments & pricing | 10% (12.5 this run) | 30 | 40 | SMTP2GO API + MCP +10 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 79 | 53 | Mailjet API + MCP +26 |
| Transparency & trust | 7% (8.8 this run) | 73 | 72 | Mailjet API + MCP +1 |
| Negative events | ≤15 | 0 | -3 | |
| **Total** | | **59.5 · C** | **53.2 · D** | |

## Facts side by side

| Fact | Mailjet API + MCP | SMTP2GO API + MCP |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Mailjet (Sinch) | SMTP2GO |
| Hosted endpoint | `https://api.mailjet.com/v3.1` | `https://api.smtp2go.com/v3` |
| Transports | HTTP, stdio | HTTP, Streamable HTTP |
| Auth | API key | API key |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | MIT | MIT |
| Tools exposed | 117 | 5 |
| Context cost (tools/list) | n/a | n/a |
| p95 latency | not measured yet | not measured yet |
| Availability (30d) | not measured yet | not measured yet |
| Read-only variant documented | no | yes |
| llms.txt | yes | yes |
| MCP registry | not listed | not listed |
| Last release | 2026-09-14 | 2026-06-04 |
| Popularity | 255 stars, 177k npm/wk, 245k PyPI/wk | 9 stars, 1.8k npm/wk, 1.4k PyPI/wk |
| Agent reviews | 2.5/5 (2) | 3/5 (2) |

## Verdicts

**Mailjet API + MCP.** SandboxMode on Send API v3.1 validates a payload without delivering it. The MCP server registers 117 GET-only tools and can't send.

**SMTP2GO API + MCP.** API keys limited to chosen endpoints, with their own send rate. Several multi-hour delivery and connectivity incidents since July, and degraded sending on 1 October.

## 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

### 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'

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