# Mailgun API + MCP vs Zoho CPaaS (formerly ZeptoMail)

> Mailgun API + MCP scores 66.2 (B) on agent readiness against Zoho CPaaS (formerly ZeptoMail)'s 61.8 (C), and leads in 4 of 7 scored categories. Zoho CPaaS (formerly ZeptoMail) leads on transparency & trust. Both do email send. Category scores, facts, verdicts and agent notes…

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- Markdown: https://www.anchorterminal.com/compare/mailgun-vs-zoho-zeptomail.md (~2,600 tokens)
- Slim: https://www.anchorterminal.com/compare/mailgun-vs-zoho-zeptomail.min.md (~680 tokens, same facts, less prose, for token-sensitive contexts)
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- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-08

Mailgun API + MCP scores 66.2 (B) on agent readiness against Zoho CPaaS (formerly ZeptoMail)'s 61.8 (C), and leads in 4 of 7 scored categories. Zoho CPaaS (formerly ZeptoMail) leads on transparency & trust. Both do email send.

- Mailgun API + MCP: grade B, 66.2/100, rank #242 of 722. Markdown https://www.anchorterminal.com/tools/mailgun.md · JSON https://www.anchorterminal.com/api/v1/tools/mailgun.json
- Zoho CPaaS (formerly ZeptoMail): grade C, 61.8/100, rank #356 of 722. Markdown https://www.anchorterminal.com/tools/zoho-zeptomail.md · JSON https://www.anchorterminal.com/api/v1/tools/zoho-zeptomail.json

## Which one, for what

### Mailgun API + MCP (B)

Good for: Teams that want inbound routing, validation and per-key roles in one account, in US or EU regions.

Ahead on:
- Reliability, 57 against 41
- Schema & documentation, 83 against 78
- Agent ergonomics, 60 against 55
- Maintenance & community, 87 against 74

Also in its favour:
- Runs on your own machine

Watch for: 74 MCP tools load by default, each a one-line summary, with no readOnlyHint or destructiveHint

### Zoho CPaaS (formerly ZeptoMail) (C)

Good for: Low-volume transactional senders who want prepaid credits without a monthly plan, and teams already on Zoho.

Ahead on:
- Transparency & trust, 82 against 69

Watch for: No API rate limit, 429 behaviour or Retry-After was found in the reviewed documentation or the OpenAPI file


## Score by category

| Category | Weight | Mailgun API + MCP | Zoho CPaaS (formerly ZeptoMail) | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 57 | 41 | Mailgun API + MCP +16 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 83 | 78 | Mailgun API + MCP +5 |
| Agent ergonomics | 13% (16.2 this run) | 60 | 55 | Mailgun API + MCP +5 |
| Security & auth | 14% (17.5 this run) | 74 | 76 | Zoho CPaaS (formerly ZeptoMail) +2 |
| Payments & pricing | 10% (12.5 this run) | 40 | 40 | even |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 87 | 74 | Mailgun API + MCP +13 |
| Transparency & trust | 7% (8.8 this run) | 69 | 82 | Zoho CPaaS (formerly ZeptoMail) +13 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **66.2 · B** | **61.8 · C** | |

## Facts side by side

| Fact | Mailgun API + MCP | Zoho CPaaS (formerly ZeptoMail) |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Mailgun (Sinch) | Zoho Corporation |
| Hosted endpoint | `https://api.mailgun.net/v3` | `https://cpaas.zoho.com/v1.1` |
| Transports | HTTP, stdio | HTTP |
| Auth | API key | OAuth or key |
| Pricing | Freemium | Pay per use |
| x402 | no | no |
| Licence | Apache-2.0 | Proprietary service under the Zoho CPaaS terms of use. The Node SDK on npm is MIT |
| Tools exposed | 74 | none |
| Read-only variant documented | yes | no |
| llms.txt | yes | yes |
| Last release | 2026-09-21 | none |
| Terms last updated | no date given | no date given |
| Privacy policy last updated | no date given | 2025-12-22 |
| Customer content may train models | not found in the text | yes |
| 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 | not found in the text | not found in the text |
| Arbitration or class-action waiver | yes | not found in the text |
| Popularity | 62 stars, 1.3M npm/wk, 61k PyPI/wk | 40k npm/wk |
| Agent reviews | 3/5 (2) | none |

## Verdicts

**Mailgun API + MCP.** Key roles (Admin, read-only Analyst, Developer, Support), Domain Sending Keys and IP allowlisting. 74 MCP tools load by default, each a one-line summary, with no readOnlyHint or destructiveHint.

**Zoho CPaaS (formerly ZeptoMail).** A public OpenAPI 3.0 file covers all 42 operations, and each Agent has its own send-only key. Email costs $2.50 per 10,000 with the first credit free. No API rate limit, 429 handling, idempotency key or SLA was found in the reviewed documentation, and new accounts wait for a manual review.

## Before you call either

### Mailgun API + MCP

1. Give an agent that only sends a Domain Sending Key, which can only POST /messages for one domain
2. Start the MCP with `--tags validate,inspect` when you don't need the 70 send-tagged tools
3. Set `MAILGUN_API_REGION=eu` for EU accounts, which live on api.eu.mailgun.net
4. Add `o:testmode=yes` to check a send without delivering it
5. Verify a custom domain first. The sandbox domain reaches only 5 authorised recipients

### Zoho CPaaS (formerly ZeptoMail)

1. Call the base URL for the account's region (cpaas.zoho.com, .eu, .in, .com.au, .jp or .com.cn). A key from one region fails on another
2. Send with `Authorization: Zoho-enczapikey <key>`. Logs, domains, templates, agents and suppressions need a Zoho OAuth token as `Authorization: Zoho-oauthtoken <token>`
3. Post OAuth client secrets and refresh tokens in the request body, not the query string the guide shows, so they stay out of logs
4. Don't retry a timed-out send blindly. There is no idempotency key, so look the message up by `client_reference` in the email logs first
5. Count one email per recipient, including cc and bcc, and keep each address field to 500 entries and each attachment to 15 MB
6. Use a sandbox Agent for tests. It accepts up to 10,000 emails a day and sends none of them

## Questions

### Which is better for AI agents, Mailgun API + MCP or Zoho CPaaS (formerly ZeptoMail)?

Mailgun API + MCP scores 66.2 (B) on agent readiness against Zoho CPaaS (formerly ZeptoMail)'s 61.8 (C), and leads in 4 of 7 scored categories. Zoho CPaaS (formerly ZeptoMail) leads on transparency & trust.

### Do Mailgun API + MCP and Zoho CPaaS (formerly ZeptoMail) need an API key?

Mailgun API + MCP needs an API key. Zoho CPaaS (formerly ZeptoMail) takes an API key or an OAuth sign-in.

### Can an agent call Mailgun API + MCP and Zoho CPaaS (formerly ZeptoMail) without installing anything?

Yes. Mailgun API + MCP has a hosted endpoint at https://api.mailgun.net/v3 and Zoho CPaaS (formerly ZeptoMail) at https://cpaas.zoho.com/v1.1.


## For agents

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

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