Zoho CPaaS (formerly ZeptoMail)

# Fix list: Zoho CPaaS (formerly ZeptoMail)

From Anchor Terminal's listing at https://www.anchorterminal.com/tools/zoho-zeptomail, the October 2026 research run, assessed 8 October 2026. Grade C, 61.8 out of 100.

This is everything the published grade says the listing lacks, the biggest possible gain to the total first. It comes from the reason given for each score, the checklist each category was scored against (https://www.anchorterminal.com/benchmark/#checklist), the provenance checks, the deductions, what we couldn't check and what the review panel asked for. A fix counts at the next check, once it's public.

For a coding agent working on Zoho CPaaS (formerly ZeptoMail): work through the items below in the product, its docs and its public pages. Each category gives the reason for its score, with the points each checklist item earned, and the checklist itself, so the gap is the items that earned less than their points. Change the product, not the wording, and keep a note of what you changed and where it's published.

## 1. Reliability, 41 out of 100, up to 11.8 more on the total

Why it scored 41: Graded on the hosted email API with the hosted lines. Zoho's status site at us.zohostatus.com lists three Zepto Mail components with status and incident history sections (20). The history loads by script and we couldn't read it. The site's RSS feed shows Zepto Mail and Zepto Mail-SMTP last changed status on 29 July 2026, in the same minute as several other Zoho services, with no duration, so this line is scored as no readable history (5). No request rate limit was found. The docs give payload caps (500 addresses a field, 60 attachments, 15 MB each) and the sandbox allowance of 10,000 emails a day (6). No 429 handling, Retry-After or idempotency key found in the docs or the OpenAPI file, whose email operations document only 200, 400 and 404 (0). No SLA found (0). The email channel is generally available, while SMS, WhatsApp and voice are marked beta (10).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-reliability):

Hosted APIs, MCP servers, models and platforms.

- 20, a public status page with component history (Statuspage, Instatus, BetterStack or the vendor's own).
- 0 to 30, the incident record for the last 90 days on that page. 30 for a clean record or trivial incidents only, 20 for minor incidents only, 10 for one major outage (an hour or more of a core API down, or errors across the board), 0 for several. 5 when there's no history we could read, and the note says so.
- 15, rate limits documented with numbers.
- 15, documented 429 or overload handling (Retry-After, backoff guidance), and idempotency keys or safe-retry guidance where writes are involved.
- 10, an SLA published for any paid tier.
- 10, the surface agents use is generally available, not beta or preview.

Local packages, SDKs, frameworks and stdio MCP servers.

- 20, installs from an official package with supported runtimes stated.
- 25, a public CI and test suite, passing on the default branch.
- 0 to 25, open crash or regression issues relative to activity (25 for few and handled, 0 for many, old and unanswered).
- 15, semver discipline and breaking changes called out in a changelog.
- 15, version 1.0 or later, or declared stable.

Protocols are read from their reference implementations, the public facilitators or servers, spec stability and test vectors.

## 2. Payments & pricing, 40 out of 100, up to 7.5 more on the total

Why it scored 40: No x402, MPP or L402 (0). $2.50 per credit of 10,000 emails and $30 a month for a dedicated IP, public without a login (20). The first credit is free, and the documented signup asks for a phone verification and no payment details (20). Signup is a browser form with phone verification, and Zoho staff review each new account, so there is no autonomous route (0).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-payments):

The published rubric, also on the [x402 page](https://www.anchorterminal.com/x402/).

- 40, a machine payment protocol (x402, MPP or L402) on the tool's own endpoints. 10 to 30 when it covers only some endpoints or only goes through a third party, and the note says which.
- 20, per-call or per-unit pricing published without a login. 10 for public plan-only pricing, 0 for "contact sales" or prices behind a login.
- 20, a free tier or trial that doesn't need a card.
- 20, autonomous onboarding, meaning an agent can get access without a person signing up in a browser (keyless use, x402, a programmatic key API).

Payment platforms and agent wallets rarely charge for their own API over a machine protocol, so the first line has steps for them, and the highest one that applies counts. 40 when x402, MPP or L402 runs on all their own endpoints, 30 when it runs on part of their own API, 25 when their merchants can accept one, 20 for running a facilitator, 15 for paying as a buyer, and 0 when the only protocol is their own. Merchant acceptance sits above a facilitator because the platform's own customers can charge agents through it, while a facilitator settles for sellers who wire up the protocol themselves. The counter-argument (a facilitator does more for the protocol as a whole) has a point. Each note says which step applied.

Open-source software you run yourself is scored on its hosted or paid option if it has one. A free, self-hosted package with nothing to buy gets 20, 20 and 20 for the last three lines, and 0 to 40 for the first only if it ships a payment protocol.

## 3. Agent ergonomics, 55 out of 100, up to 7.3 more on the total

Why it scored 55: Send responses are small, and the logs endpoint takes offset and limit, with no field selection (15). Thirteen filters on email logs, among them recipient, subject, date range, `client_reference` and bounce or delivery state (16). Errors carry a code, a sub-code and a message, and the docs pair each with a fix (16). No idempotency key and no guidance on retrying a send (0). A send needs only from, to and subject. The one official SDK found is for Node, and managing the account needs a second credential type (8).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-ergonomics):

- 0 to 25, context cost. For MCP, the number and size of the tool definitions (25 for ten or fewer compact tools, 15 for 11 to 30, 5 for more than 30, plus up to 10 back for toolsets, dynamic loading or read-only subsets). For APIs, whether responses can be sized (field selection, limits, summaries).
- 20, pagination, filtering and output-size controls.
- 20, actionable, documented error responses, codes and messages an agent can recover from.
- 20, idempotency or safe retries, and for MCP the `readOnlyHint` and `destructiveHint` annotations.
- 15, sensible defaults, few required parameters, and official SDKs in at least two languages.

Models are read for tool use, structured output, prompt caching, context length, batch and SDKs. Frameworks for how much code and how many defaults a tool-calling agent with MCP needs.

## 4. Security & auth, 76 out of 100, up to 4.2 more on the total

Why it scored 76: Send keys are per Agent and per channel, can be created, listed and deleted by API, and can only send and upload attachments. Management calls use Zoho OAuth 2.0 with READ, CREATE, UPDATE and DELETE scopes per resource and one-hour access tokens. That earns 30, less 10 because the OAuth guide documents the client secret and refresh token in the token URL's query string (20). Read-only scopes, send-only keys, sandbox Agents and IP allow lists for sending, the REST API and the web console. No approval step for deletes (15). No inbound mail, so responses hold only the account's own logs and settings (10). Activity logs per user kept one year with export, and email logs for 60 days that show the triggering IP (13). security.txt valid until 30 June 2028, a bug bounty, and SOC 2 Type II and ISO/IEC 27001 on Zoho's compliance page. No public advisory feed found (18).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-security):

- 0 to 30, the credential model. 30 for OAuth 2.1 with scopes, or scoped and revocable keys with rotation. 20 for plain revocable API keys. 10 for one all-powerful key. 10 off when a secret can travel in a URL query string as a documented option.
- 0 to 20, read-only or least-privilege modes, and confirmation or approval for destructive actions.
- 0 to 15, prompt-injection posture where the tool returns untrusted content (documented mitigations or guidance). A tool that returns no untrusted content gets 10.
- 0 to 15, audit logs or per-call visibility for the operator.
- 0 to 20, a security programme. security.txt or a disclosure policy, a bug bounty, SOC 2 or ISO 27001, advisories handled in public.

Models are read for retention, whether API data trains models (and whether that's off by default), zero-retention options and certifications. Frameworks for telemetry defaults, approval hooks, guardrails and sandboxing.

## 5. Schema & documentation, 78 out of 100, up to 3.6 more on the total

Why it scored 78: One public OpenAPI 3.0.3 file with 42 operations, linked from the docs without a login (25). llms.txt at zoho.com/cpaas/llms.txt and a second for the help centre, with a Markdown copy of each page (10). Every operation has a description, most of them one sentence, with nothing on when not to use it (10). Request bodies name required fields and length caps, with 9 enums across the file, but log filters take dates as free strings and responses are typed as a bare JSON object (10). Sample requests and responses on every page and an error-code table of 24 rows with remedies. The 401 body we got from the live endpoint has a different shape from the documented sample (11). Version 1.1 in the path and a What's New page dated by month only (12).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-schema):

APIs and MCP servers.

- 25, a machine-readable contract (a public OpenAPI file or similar; for MCP, typed JSON Schema inputs on every tool).
- 10, llms.txt or Markdown docs served for agents.
- 0 to 20, descriptions that say what a tool is for, when to use it and when not to, read from the tool definitions in the source or the API reference.
- 0 to 15, typed inputs with enums, constraints and required fields, and no free-form JSON blobs.
- 0 to 15, examples and documented error responses.
- 15, versioning and a public changelog.

Models are read from the API reference, the OpenAPI file, llms.txt, the structured-output and tool-use docs and the model cards. Frameworks from docs a model can follow, typed interfaces, examples and the API reference.

## 6. Maintenance & community, 74 out of 100, up to 2.3 more on the total

Why it scored 74: The What's New page dates entries by month. The newest is the September 2026 rename with new SMS, WhatsApp and voice endpoints, and help pages carry dates up to 6 October 2026, so we counted it as within 30 days (30). Entries for September, August and July 2026 fall in the last 90 days, though the July one may predate 10 July (20). A public changelog, a support address and a contact page that says support runs around the clock. We saw no public forum replies (10). The Node SDK zeptomail 8.0.1 is from 29 May 2026 with about 40,000 weekly downloads, and it is the only official SDK found (10). The npm package names no source repository, so CI and dependency health couldn't be read (4).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-maintenance):

- 0 to 30, time since the last release, or the last published model or API change for a closed service. 30 within 30 days, 20 within 90, 10 within 180, 0 older.
- 20, at least three releases or dated changelog entries in the last 90 days.
- 0 to 25, responsiveness. Issues and pull requests answered on GitHub (the open issues and how recent the replies are). For closed services, a public changelog and a support or community channel that answers, 0 to 15.
- 15, presence in the official MCP registry under a verified namespace (MCP servers), or current official SDKs (APIs and models).
- 10, package health, current dependencies and CI.

Models are read for deprecation notice periods and model churn rather than release counts.

## 7. Transparency & trust, 82 out of 100, up to 1.6 more on the total

Made of editorial 69, provenance 94.

Why it scored 82: Closed service with its own published terms of use, and an MIT Node SDK (20). Zoho's privacy policy of 22 December 2025 covers service data, and the CPaaS pages say content is stored only on opt-in for 60 days and logs for 60 days. The pages disagree on deletion. The GDPR page says account data is deleted within 24 hours of a 48-hour grace period, the privacy policy says a clean-up every six months with backups three months later, and the April 2026 changelog entry says content can be kept up to 50 days (18). The terms commit to a six-month deprecation period after a service announcement, with no dated notices to check it against (16). Six data centre regions are named with their hosts, and Zoho publishes a sub-processor directory by service that loads by script and that we couldn't read (15).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-transparency):

- 0 to 30, source availability and licence clarity. 30 for open source under an OSI licence, 15 for closed with clear terms, 0 for unclear terms.
- 0 to 30, data handling and retention statements that agree with each other (privacy policy, DPA, retention periods, subprocessors).
- 0 to 20, a deprecation policy or notices with dates.
- 0 to 20, telemetry disclosed with an opt-out (local software), or subprocessors and data locations disclosed (hosted).

The other half of Transparency and trust is the provenance score, computed from checked facts (below). The category score is the mean of the two.

Provenance checks not met in full (half of this category, computed from checked facts):

- Terms of service: read, states 2 of the 7 things a reader expects (5.7 of 10)
- Privacy policy: read, states 8 of the 8 things a reader expects, and has 1 clause that costs points (8 of 10)

## What we couldn't check

What we couldn't read counted as absent. Publishing it on a page a plain HTTP fetch can read (not only in a browser) lets the next check count it.

- The lead named the product Zoho ZeptoMail. It was renamed Zoho CPaaS in September 2026, and the API host in the docs is now cpaas.zoho.com
- unchecked: incident history on us.zohostatus.com, which loads by script. Only the RSS feed's last status change (29 July 2026) was read
- unchecked: Zoho's sub-processor directory entries for Zoho CPaaS, which load by script
- unchecked: whether the Zoho MCP product listed on the status page exposes Zoho CPaaS. Nothing in the CPaaS docs mentions an MCP server
- Whether a request rate limit exists and what a throttled call returns
- Whether signup ever asks for a card. The documented steps don't
- The day in September 2026 of the rename, and whether the July 2026 changelog entry falls inside the last 90 days
- Whether bounced or rejected sends use credit
- No data processing addendum was looked for beyond the GDPR page
- `lastRelease` is left empty because the newest changelog entry is dated September 2026 with no day. The newest release with a full date is the Node SDK 8.0.1 on 29 May 2026

## Weaknesses

- No API rate limit, 429 behaviour or Retry-After was found in the reviewed documentation or the OpenAPI file
- No idempotency key on send. `client_reference` is a tracking label only
- Every new account is reviewed by Zoho staff, which the docs say takes two business days, before credits can be bought
- The only official SDK found is the Node package, last published on 29 May 2026 and still named zeptomail
- The OAuth guide puts the client secret and refresh token in the token URL's query string
- No inbound email, and no SLA was found

## What costs an agent a turn today

The notes we give agents before they call it. Each one is a workaround an agent shouldn't need.

- 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
- Send with `Authorization: Zoho-enczapikey <key>`. Logs, domains, templates, agents and suppressions need a Zoho OAuth token as `Authorization: Zoho-oauthtoken <token>`
- Post OAuth client secrets and refresh tokens in the request body, not the query string the guide shows, so they stay out of logs
- 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
- Count one email per recipient, including cc and bcc, and keep each address field to 500 entries and each attachment to 15 MB
- Use a sandbox Agent for tests. It accepts up to 10,000 emails a day and sends none of them

## When it's done

Send what changed and where it's published as a dispute (https://www.anchorterminal.com/builders/#disputes, or `POST https://www.anchorterminal.com/api/v1/contact` with `"kind": "dispute"`). Disputes are answered in public, and the listing is checked again by the same checklist. Paying for an audit or a listing claim changes nothing here.