# Zoho CPaaS (formerly ZeptoMail) (slim)

> Transactional email service from Zoho, renamed from ZeptoMail to Zoho CPaaS in September 2026. It sends application email through a REST API or SMTP relay, with templates, domain management, suppression lists, logs and webhooks.

- Full: https://www.anchorterminal.com/tools/zoho-zeptomail.md (~7,850 tokens) · this version ~1,830 tokens · JSON https://www.anchorterminal.com/tools/zoho-zeptomail.json · canonical https://www.anchorterminal.com/tools/zoho-zeptomail
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · Updated: 2026-10-08

**C · 61.8/100 · rank #356 of 722 · #10 in Email delivery APIs · not agent-ready · confidence medium**


Assessment: 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.

## Facts

- Kind: HTTP API · vendor: Zoho Corporation · category: Email delivery APIs · legal entity: Zoho Corporation · provenance 94/100
- Endpoint: `https://cpaas.zoho.com/v1.1` (HTTP)
- Auth: OAuth or key · pricing: Pay per use · x402: no · licence: Proprietary service under the Zoho CPaaS terms of use. The Node SDK on npm is MIT
- Probe metrics: not measured yet (probes haven't run)
- Rename: ZeptoMail became Zoho CPaaS in September 2026, adding SMS (India only), WhatsApp and voice, all three marked beta. zoho.com/zeptomail redirects to zoho.com/cpaas. api.zeptomail.com still answered on 8 October 2026
- API: REST, version 1.1, 42 operations in one OpenAPI 3.0.3 file. 33 cover email (send, batch, templates, file cache, logs, domains, agents, suppressions), 9 cover voice, SMS and WhatsApp
- Regions: Six data centres with their own base URL. US cpaas.zoho.com, EU cpaas.zoho.eu, India cpaas.zoho.in, Australia cpaas.zoho.com.au, Japan cpaas.zoho.jp, China cpaas.zoho.com.cn
- Credentials: Send key per Agent and per channel in the `Authorization` header with the prefix Zoho-enczapikey. Zoho OAuth 2.0 (authorisation code grant, one-hour access tokens, refresh tokens) for management calls, with scopes such as Zeptomail.Domains.READ
- SMTP: smtp.zeptomail.com on port 587 (TLS) or 465 (SSL), username emailapikey, TLS 1.2
- Limits: 500 addresses per to, cc or bcc field, 60 attachments, 15 MB per attachment, 500 characters in a subject. No request rate limit found. An owner can set a daily blocking limit per Agent
- Free allowance: First credit free, 10,000 emails. Unreviewed accounts have a daily sending limit and can't buy credits
- Sandbox: Up to 2 sandbox Agents, 10,000 emails a day each, nothing sent to recipients, simulated bounces and webhooks
- Logs: Email logs kept 60 days and readable by API with offset, limit and 13 filters. Content is stored only if the owner opts in. Account activity logs kept one year
- Webhooks: Soft bounce, hard bounce, open, click and feedback loop events per Agent
- Inbound: None
- Dedicated IP: $30 a month, billed annually, in some data centres
- SDK: Node package zeptomail 8.0.1 (29 May 2026, MIT, Node 20 or later, TypeScript types). Code samples for curl, C#, Python, PHP and Java, and a Postman collection
- Certifications: Zoho lists SOC 2 Type II, SOC 1 Type II, ISO/IEC 27001, 27701, 27017 and 27018 on its compliance page, and runs a bug bounty at bugbounty.zohocorp.com
- Prices: Email credit $0.25 per 1,000 emails; Dedicated IP $30 per month (plan)

- Scores: Reliability 41, Performance pending, Schema & documentation 78, Agent ergonomics 55, Security & auth 76, Payments & pricing 40, Task success pending, Maintenance & community 74, Transparency & trust 82 · total over the 7 assessed categories
- Why: Reliability, Graded on the hosted email API with the hosted lines. · Schema & documentation, One public OpenAPI 3.0.3 file with 42 operations, linked from the docs without a login (25). · Agent ergonomics, Send responses are small, and the logs endpoint takes offset and limit, with no field selection (15). · Security & auth, Send keys are per Agent and per channel, can be created, listed and deleted by API, and can only send and upload attachments. · Payments & pricing, No x402, MPP or L402 (0). · Maintenance & community, The What's New page dates entries by month. · Transparency & trust, Closed service with its own published terms of use, and an MIT Node SDK (20).
- Sources: 27, open questions: 10, both in the full twin
- Capabilities: email.send, email.templates, email.domains, email.analytics
- JSON: https://www.anchorterminal.com/api/v1/tools/zoho-zeptomail.json
- Verify (for the vendor): the badge `https://www.anchorterminal.com/badges/zoho-zeptomail.svg` or a link to https://www.anchorterminal.com/tools/zoho-zeptomail from a page on zoho.com or one of its subdomains, then `POST https://www.anchorterminal.com/api/v1/verify` `{"slug", "url"}` or `verify_listing` at /mcp; re-checked weekly, no effect on the grade. Snippets in the full twin.

## Before you call it

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

## Connect

```bash
npm install zeptomail
```

```bash
curl --request POST --url https://cpaas.zoho.com/v1.1/email \
  --header 'Authorization: Zoho-enczapikey REPLACE_WITH_YOUR_KEY' \
  --header 'content-type: application/json' \
  --data '{"from":{"address":"hello@yourapp.com","name":"Your App"},"to":[{"email_address":{"address":"user@example.com","name":"User"}}],"subject":"Test Email","htmlbody":"<p>Test email sent successfully.</p>"}'
```
Full config and headless snippets are in the full page. Through letme (picks today, calling later): https://letme.dev/zoho-zeptomail

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## Panel reviews (0, desk reviews from public material, no calls made)