--- title: REST API description: Send emails from any application using the Email Service REST API with standard HTTP requests. image: https://developers.cloudflare.com/dev-products-preview.png --- > Documentation Index > Fetch the complete documentation index at: https://developers.cloudflare.com/email-service/llms.txt > Use this file to discover all available pages before exploring further. [Skip to content](#%5Ftop) # REST API The REST API allows you to send emails from any application using a standard HTTP request to `POST /accounts/{account_id}/email/sending/send`. Use it from any backend, serverless function, or CI/CD pipeline — no Cloudflare Workers binding is required. For the full OpenAPI specification, refer to the [Email Sending API reference](https://developers.cloudflare.com/api/resources/email%5Fsending/methods/send/). Cloudflare also provides official SDKs for the REST API: [Node](https://developers.cloudflare.com/api/node/), [Python](https://developers.cloudflare.com/api/python/), and [Go](https://developers.cloudflare.com/api/go/). ## Authentication Authenticate with a [Cloudflare API token](https://developers.cloudflare.com/fundamentals/api/get-started/create-token/) that has permission to send emails. Include it in the `Authorization` header: ``` Authorization: Bearer ``` ## Send an email Terminal window ``` curl "https://api.cloudflare.com/client/v4/accounts/{account_id}/email/sending/send" \ --header "Authorization: Bearer " \ --header "Content-Type: application/json" \ --data '{ "to": "recipient@example.com", "from": "welcome@yourdomain.com", "subject": "Welcome to our service!", "html": "

Welcome!

Thanks for signing up.

", "text": "Welcome! Thanks for signing up." }' ``` For multiple recipients, CC/BCC, and named addresses, see [Specify recipients](https://developers.cloudflare.com/email-service/examples/email-sending/recipients/). ## Attachments Send files by including base64-encoded content in the `attachments` array. The total message size must not exceed **5 MiB** (including attachments). Terminal window ``` curl "https://api.cloudflare.com/client/v4/accounts/{account_id}/email/sending/send" \ --header "Authorization: Bearer " \ --header "Content-Type: application/json" \ --data '{ "to": "customer@example.com", "from": "invoices@yourdomain.com", "subject": "Your Invoice", "html": "

Invoice attached

Please find your invoice attached.

", "attachments": [ { "content": "JVBERi0xLjQKJeLjz9MK...", "filename": "invoice-12345.pdf", "type": "application/pdf", "disposition": "attachment" } ] }' ``` For inline images and file uploads, see [Email attachments](https://developers.cloudflare.com/email-service/examples/email-sending/email-attachments/). ## Custom headers Set custom headers for threading, list management, or tracking. Refer to the [email headers reference](https://developers.cloudflare.com/email-service/reference/headers/) for the full list of allowed headers. Terminal window ``` curl "https://api.cloudflare.com/client/v4/accounts/{account_id}/email/sending/send" \ --header "Authorization: Bearer " \ --header "Content-Type: application/json" \ --data '{ "to": "user@example.com", "from": "notifications@yourdomain.com", "subject": "Your weekly digest", "html": "

Weekly Digest

", "headers": { "List-Unsubscribe": "", "List-Unsubscribe-Post": "List-Unsubscribe=One-Click", "X-Campaign-ID": "weekly-digest-2026-03" } }' ``` ## Response A successful response returns the delivery status for each recipient: ``` { "success": true, "errors": [], "messages": [], "result": { "delivered": ["recipient@example.com"], "permanent_bounces": [], "queued": [] }} ``` * `delivered` \- Email addresses to which the message was delivered immediately * `permanent_bounces` \- Email addresses that permanently bounced * `queued` \- Email addresses for which delivery was queued for later Workers binding vs REST API responses The REST API returns recipient-grouped delivery status. The [Workers binding](https://developers.cloudflare.com/email-service/api/send-emails/workers-api/) returns a single `messageId` per `send()` call instead. ## Error handling The REST API returns standard Cloudflare API error responses. A failed request returns an `errors` array with numeric error codes and machine-readable messages: ``` { "success": false, "errors": [ { "code": 10001, "message": "email.sending.error.invalid_request_schema" } ], "messages": [], "result": null} ``` REST API error codes: | HTTP Status | Code | Message | Description | | ----------- | ----- | --------------------------------------------------- | ---------------------------------------------- | | 400 | 10001 | email.sending.error.invalid\_request\_schema | Invalid request format | | 400 | 10200 | email.sending.error.email.too\_big | Email exceeds size limit | | 400 | 10201 | email.sending.error.email.no\_content\_length | Missing content length | | 400 | 10202 | email.sending.error.email.invalid | Invalid email content | | 401 | 10101 | email.sending.error.authentication.unauthorized | Missing or invalid API token | | 401 | 10103 | email.sending.error.authentication.bad\_token\_type | Wrong token type for this endpoint | | 403 | 10102 | email.sending.error.authentication.forbidden | Token lacks permission to send | | 403 | 10105 | email.sending.error.authentication.not\_entitled | Account not entitled to use Email Sending | | 403 | 10203 | email.sending.error.email.sending\_disabled | Sending disabled for this zone or account | | 404 | 10000 | email.sending.error.not\_found | Resource not found | | 429 | 10004 | email.sending.error.throttled | Rate limit exceeded | | 500 | 10002 | email.sending.error.internal\_server | Internal server error | | 500 | 10003 | email.sending.error.not\_implemented | Operation not implemented | | 503 | 10100 | email.sending.error.authentication.upstream | Authentication service temporarily unavailable | Workers binding vs REST API errors The REST API returns standard Cloudflare API numeric error codes, while the [Workers binding](https://developers.cloudflare.com/email-service/api/send-emails/workers-api/) throws errors with string codes (for example, `E_SENDER_NOT_VERIFIED`). Refer to the [Workers API error codes table](https://developers.cloudflare.com/email-service/api/send-emails/workers-api/#error-codes) for the string error codes. ## Next steps * Refer to the [Email Sending API reference](https://developers.cloudflare.com/api/resources/email%5Fsending/methods/send/) for the full request and response schemas. * See the [Workers API](https://developers.cloudflare.com/email-service/api/send-emails/workers-api/) for sending emails directly from Cloudflare Workers using bindings. * See [SMTP](https://developers.cloudflare.com/email-service/api/send-emails/smtp/) for sending from any SMTP-capable application or mail client. * Review [email headers](https://developers.cloudflare.com/email-service/reference/headers/) for threading, list management, and custom tracking headers. ```json {"@context":"https://schema.org","@type":"TechArticle","@id":"https://developers.cloudflare.com/email-service/api/send-emails/rest-api/#page","headline":"REST API · Cloudflare Email Service docs","description":"Send emails from any application using the Email Service REST API with standard HTTP requests.","url":"https://developers.cloudflare.com/email-service/api/send-emails/rest-api/","inLanguage":"en","image":"https://developers.cloudflare.com/dev-products-preview.png","dateModified":"2026-06-09","publisher":{"@type":"Organization","name":"Cloudflare","url":"https://www.cloudflare.com/"},"isPartOf":{"@type":"WebSite","@id":"https://developers.cloudflare.com/#website","name":"Cloudflare Docs","url":"https://developers.cloudflare.com/"}} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/directory/","name":"Directory"}},{"@type":"ListItem","position":2,"item":{"@id":"/email-service/","name":"Email Service"}},{"@type":"ListItem","position":3,"item":{"@id":"/email-service/api/","name":"API reference"}},{"@type":"ListItem","position":4,"item":{"@id":"/email-service/api/send-emails/","name":"Send emails"}},{"@type":"ListItem","position":5,"item":{"@id":"/email-service/api/send-emails/rest-api/","name":"REST API"}}]} ```