Cloudflare Email Service

# Fix list: Cloudflare Email Service

From Anchor Terminal's listing at https://www.anchorterminal.com/tools/cloudflare-email-service, the October 2026 research run, assessed 8 October 2026. Grade B, 67.3 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 Cloudflare Email Service: 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, 51 out of 100, up to 9.8 more on the total

Why it scored 51: Graded on the hosted Email Sending REST API with the hosted lines. cloudflarestatus.com is a Statuspage with Email Sending and Email Routing as separate components (20). The incidents feed held 50 incidents from 19 September to 8 October 2026, none naming either email component. The API component had a minor incident of 18 minutes on 7 October and delayed permission changes on 30 September. The history page loads by script, so the rest of the 90 days went unread (10 of 30). 1,200 API requests per five minutes per token and 200 a second per IP, 50 recipients and 5 MiB per message. The daily sending quota and the send rate limit have no published number (12 of 15). The send endpoint documents 429 with code 10004, the Cloudflare API returns `retry-after` and `Ratelimit` headers, and the SDKs back off. No idempotency key for sends (9 of 15). No SLA found, and the agreement gives no commitment for beta services (0). Email Sending is marked Beta in the docs, although the OpenAPI operation is tagged generally-available. We scored from the docs (0).

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, 30 out of 100, up to 8.8 more on the total

Why it scored 30: No x402, MPP or L402 on the Email Sending endpoints (0). $0.35 per 1,000 emails after 3,000 a month, and the $5 Workers Paid minimum, are public without a login (20). The only free sending is to the account's own verified destination addresses, on any plan. Arbitrary recipients need the paid plan, and we didn't check whether signup asks for a card (10 of 20). An account, an API token and a domain on Cloudflare DNS are set up by a person in the dashboard (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, 72 out of 100, up to 4.6 more on the total

Why it scored 72: A send returns a small object grouping recipients into delivered, queued and bounced. Send events are read through the GraphQL Analytics API, where the caller picks fields (18 of 25). Suppression lists page by cursor with `per_page` up to 1,000 and filters for email, reason and scope. The GraphQL datasets filter by status, date and domain (17 of 20). REST errors carry a numeric code and a machine-readable message, SMTP returns enhanced status codes with a troubleshooting section, and the binding throws string codes (18 of 20). No idempotency key on send or `send_raw`. Only the DNS re-apply call is described as idempotent (4 of 20). A send needs `to`, `from`, `subject` and one body field, and Cloudflare publishes SDKs for Node, Python and Go (15).

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, 77 out of 100, up to 4 more on the total

Why it scored 77: Cloudflare API tokens are revocable and scoped by permission, with separate send and read permissions, an optional expiry and an IP address filter. A send token covers every onboarded domain on the account, and the OpenAPI operation also accepts the legacy global API key (27 of 30). A read-only permission exists, and a Workers binding can be limited to named sender or destination addresses. Accounts without a sending domain can reach only verified addresses. No approval step for sends or deletes (14 of 20). Sending returns no untrusted content, but Email Routing hands inbound mail to Worker code and the docs suggest email as a way to drive agents, with no prompt-injection guidance found (6 of 15). Account audit logs record domain and suppression changes for 18 months, and each send is visible in the activity log and GraphQL datasets for about 30 days (14 of 15). security.txt names HackerOne and a disclosure policy with no Expires field. The compliance page lists no certifications without a dashboard login, so none were confirmed (16 of 20).

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. Transparency & trust, 76 out of 100, up to 2.1 more on the total

Made of editorial 57, provenance 95.

Why it scored 76: Closed service under the Self-Serve Subscription Agreement and service-specific terms with an Email Service section updated on 28 September 2026. The SDKs are Apache-2.0 (18 of 30). The privacy policy of 4 November 2025 makes Cloudflare a processor of customer content and a DPA is published. The docs give about seven days for message previews, 31 days for send events and 18 months for audit logs. The terms say message content may be scanned by automated tools. No retention period for message content in transit or queued was found (20 of 30). No deprecation policy found. The agreement lets Cloudflare change or end a service without notice and remove a beta service at any time (4 of 20). The sub-processor list, last updated 1 October 2025, names Google and Oracle for the Developer Platform with locations. Where email is processed isn't stated (15 of 20).

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 7 of the 7 things a reader expects, and has 2 clauses that cost points (6 of 10)
- Privacy policy: read, states 7 of the 8 things a reader expects (9.3 of 10)

## 6. Schema & documentation, 89 out of 100, up to 1.8 more on the total

Why it scored 89: Cloudflare's public OpenAPI 3.0.3 file has 29 operations under `/email/sending` and 46 under `/email/routing` (25). llms.txt for the product and a Markdown copy of every docs page (10). Operation descriptions state the purpose and the guides say when to pick REST, the binding or SMTP, with little on when not to call an operation (14 of 20). Address fields are typed as a string, a named object or an array, attachments use a discriminator on `disposition`, and error messages are enums. Custom headers are a free map (12 of 15). Request samples in curl, TypeScript, Python, Go and Terraform, a table of 14 REST error codes and 20 binding codes. The guide's sample response omits `message_id` and `suppressed_recipients`, and its error table omits the 409 the OpenAPI file documents (13 of 15). Version in the path (`/client/v4`) and a dated product changelog with RSS (15).

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.

## 7. Maintenance & community, 81 out of 100, up to 1.7 more on the total

Why it scored 81: Read for a closed service. The newest Email Service changelog entry is 25 September 2026, per-domain suppressions (30). Four entries in the last 90 days, on 15 July, 17 July, 4 September and 25 September (20). A public changelog with RSS, a community forum and a developer Discord. We didn't sample reply times (10 of 15). The `cloudflare` SDKs on npm (7.3.0) and PyPI (5.9.0) were both published on 3 October 2026. The Go SDK wasn't checked (15). The OpenAPI file carries the sending paths. Nothing else to measure for a hosted endpoint (6 of 10).

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.

## 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.

- unchecked: status history before 19 September 2026. The history page loads by script and the incidents feed holds only the latest 50 incidents
- unchecked: Cloudflare's certifications. The compliance page lists none without a dashboard login
- unchecked: whether Cloudflare signup or the Workers Free plan asks for a card. The signup flow wasn't run
- unchecked: the Go SDK's current version and whether the SDKs' generated methods cover every sending operation
- The daily sending quota for a new account and the send rate limit have no published number
- Docs and OpenAPI disagree on status. The docs mark Email Sending as Beta, and the OpenAPI send operation is tagged generally-available
- The token permissions reference page has no Email Sending entry. The permission names come from the SMTP guide and the OpenAPI file
- Whether the legacy `/email/sending/suppression` paths in the OpenAPI file, alongside the newer `/suppressions` ones, are due for removal
- Whether Cloudflare's MCP servers, listed separately as cloudflare-mcp, expose Email Sending. Not checked for this listing
- The lead was right about the interfaces and the beta status. Email Routing is part of the same product, so the listing also covers inbound mail

## Weaknesses

- Email Sending has been in public beta since 16 April 2026. Cloudflare's terms let it remove a beta service at any time, and no SLA was found
- No idempotency key on `/email/sending/send`, in the docs or the OpenAPI file
- The daily sending quota for new accounts is described as conservative with no number. It can be read per account from `/email/sending/limits`
- The sending domain must use Cloudflare DNS, and sending to arbitrary recipients needs the Workers Paid plan at $5 a month
- A token with the send permission can send from every onboarded domain on the account. No per-domain token scope was found
- No template storage, and the terms and FAQ allow transactional email only

## 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.

- POST to `https://api.cloudflare.com/client/v4/accounts/{account_id}/email/sending/send` with `Authorization: Bearer <token>`. The body needs `to`, `from`, `subject` and one of `html` or `text`
- Don't retry a timed-out send blindly. There is no idempotency key, so look for the message in the `emailSendingAdaptive` GraphQL dataset first
- On 429 (code 10004) wait for the `retry-after` header. On 409 `sending_not_ready` the domain setup is unfinished and nothing was sent
- Read `result.delivered`, `result.queued` and `result.permanent_bounces` in the response. A 200 does not mean every recipient was accepted
- Keep to 50 recipients across to, cc and bcc, and 5 MiB per message including attachments
- For SMTP use `smtp.mx.cloudflare.net` on port 465 with implicit TLS, username `api_token` and the API token as password. Port 587 is not supported
- By default one suppressed recipient fails the whole send. Turn on Drop suppressed recipients for the domain to send to the rest

## 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.