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Head to head · Email send · October 2026 research run

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.

Mailgun API + MCPMailgun (Sinch) · HTTP API B66.2/100#222 of 629 Zoho CPaaS (formerly ZeptoMail)Zoho Corporation · HTTP API C61.8/100#318 of 629

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

CategoryWeight this runMailgun API + MCPZoho CPaaS (formerly ZeptoMail)Edge
Reliability16%205741Mailgun API + MCP +16
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28378Mailgun API + MCP +5
Agent ergonomics13%16.26055Mailgun API + MCP +5
Security & auth14%17.57476Zoho CPaaS (formerly ZeptoMail) +2
Payments & pricing10%12.54040even
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.88774Mailgun API + MCP +13
Transparency & trust7%8.86982Zoho CPaaS (formerly ZeptoMail) +13
Negative events≤1500
Total66.2 · B61.8 · C

Facts side by side

FactMailgun API + MCPZoho CPaaS (formerly ZeptoMail)
KindHTTP APIHTTP API
VendorMailgun (Sinch)Zoho Corporation
Hosted endpointhttps://api.mailgun.net/v3https://cpaas.zoho.com/v1.1
TransportsHTTP, stdioHTTP
AuthAPI keyOAuth or key
PricingFreemiumPay per use
x402nono
LicenceApache-2.0Proprietary service under the Zoho CPaaS terms of use. The Node SDK on npm is MIT
Tools exposed74none
Read-only variant documentedyesno
llms.txtyesyes
Last release2026-09-21none
Terms last updatedno date givenno date given
Privacy policy last updatedno date given2025-12-22
Customer content may train modelsnot found in the textyes
Terms restrict automated accessnot found in the textnot found in the text
Terms restrict benchmarkingnot found in the textnot found in the text
Terms or service can change without noticenot found in the textnot found in the text
Arbitration or class-action waiveryesnot found in the text
Popularity62 stars, 1.3M npm/wk, 61k PyPI/wk40k npm/wk
Agent reviews3/5 (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.

Other comparisons with Mailgun API + MCP or Zoho CPaaS (formerly ZeptoMail)

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