Cloudflare Email

Cloudflare Email Service (Sending)

Send outbound email from a Cloudflare-hosted domain via REST API or Workers binding. Complements Cloudflare Email Routing (inbound-only) to give a domain full send/receive with no mailbox provider.

When to Use vs Not Use

Use when:

• Sending programmatically (alerts, transactional mail, one-off scripts)
• Domain is already on Cloudflare DNS
• You don't need a human-facing inbox / "Sent" folder

Do NOT use when:

• User wants to send from Gmail, Apple Mail, Thunderbird, or any SMTP client (Cloudflare exposes no SMTP endpoint — use Zoho/Workspace/Fastmail instead)
• User needs IMAP, a Sent folder, or threaded reply UI
• Sending from a domain not on Cloudflare DNS

Prerequisites

1. Domain on Cloudflare DNS — zone active, nameservers delegated.
2. Email Service enabled — Dashboard → your domain → Email → Email Service → enable. This auto-adds MX/SPF/DKIM/DMARC records on a cf-bounce.<yourdomain> subdomain for bounce handling and authentication. Do not delete those records.
3. Account ID — dashboard sidebar, or wrangler whoami.
4. API Token — https://dash.cloudflare.com/profile/api-tokens → Create Token → custom token with Email Sending: Edit permission scoped to your account. Save as CF_API_TOKEN.
5. Verified sender — the from address must be on a domain where Email Service is enabled. Cloudflare rejects sends from unverified domains.

export CF_ACCOUNT_ID="your-account-id"
export CF_API_TOKEN="your-api-token"

Send via REST API

curl -sS "https://api.cloudflare.com/client/v4/accounts/$CF_ACCOUNT_ID/email/sending/send" \
  -H "Authorization: Bearer $CF_API_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "from":    "you@yourdomain.com",
    "to":      "recipient@example.com",
    "subject": "Subject line",
    "text":    "Plain text body.",
    "html":    "<p>HTML body.</p>"
  }'

A 200 with "success": true means queued for delivery. A 400 usually means the sender domain isn't verified or Email Service isn't enabled on it.

Payload Fields

Send from a Markdown File

Common one-off: turn a hand-written markdown draft into a sent email. See scripts/send-email.sh in this skill for a working helper. Usage:

./send-email.sh \
  --from you@yourdomain.com \
  --to   recipient@example.com \
  --subject "Subject line" \
  --body draft.md

It strips markdown for the text field, renders minimal HTML for the html field, and POSTs to the API.

Send via Workers Binding

When sending from a Worker, use the binding instead of the REST API — lower latency, no token management:

# wrangler.toml
send_email = [
  { name = "SEND_EMAIL" }
]

import { EmailMessage } from "cloudflare:email";
import { createMimeMessage } from "mimetext";

export default {
  async fetch(req, env) {
    const msg = createMimeMessage();
    msg.setSender({ name: "App", addr: "you@yourdomain.com" });
    msg.setRecipient("recipient@example.com");
    msg.setSubject("Hello");
    msg.addMessage({ contentType: "text/plain", data: "Body" });

    await env.SEND_EMAIL.send(new EmailMessage(
      "you@yourdomain.com",
      "recipient@example.com",
      msg.asRaw()
    ));
    return new Response("sent");
  }
}

Common Errors

Receiving Replies

Cloudflare Email Service handles outbound only. To receive replies:

• Enable Email Routing on the same domain (separate product, same dashboard)
• Add a routing rule: you@yourdomain.com → forward to a real inbox (Gmail, iCloud, etc.)
• Replies then land in that inbox; you reply from that inbox's UI (which may itself need a Send-as alias to preserve the custom-domain from)

Viewing Sent Mail

Dashboard → your domain → Email Service → Email Sending → Activity Log lists recent sends, destinations, and delivery status. Logs can take up to ~2 minutes to appear.

Only mail sent through Cloudflare (REST API or Workers binding) shows up. Mail that happens to use a from address on a Cloudflare-verified domain but is relayed by another service (e.g. Gmail's smtp.gmail.com delivering a "Send mail as" alias) bypasses Cloudflare entirely and will NOT appear in the Activity Log — this is a common point of confusion when debugging whether a send actually went through this service.

Session detail view exposes the RFC 5322 Message-ID (e.g. <NpkoCxVOvUVmswnF9h9vvVjiZoW9lgivY4xH@yourdomain.com>). Useful for:

• Matching bounces (bounce reports reference the Message-ID)
• Threading with the recipient's reply in their mail client
• Correlating with external logs if you shipped the payload to your own logger

The Message-ID is not returned in the POST /email/sending/send HTTP response — you only see it in the dashboard session view or embedded in the delivered email's headers.

No API to Retrieve Sent Content

Cloudflare exposes no endpoint to list past sends, fetch a message by ID, or retrieve a previously-sent body. The send endpoint's 200 response body does not include a message_id either. If you need an audit trail of what was actually delivered:

• Log the JSON payload yourself before calling the API (disk, database, logging service)
• Or save a copy to an inbox you control via bcc

Do not rely on Cloudflare to store or resurface outbound content.

Limitations

• No SMTP. This is the single biggest footgun — users frequently ask to point Gmail Send-as at Cloudflare. It does not work and cannot work. Redirect them to a real mailbox provider if they need SMTP.
• Per-account rate limits apply. Check current limits in Cloudflare docs — exceed them and sends queue or reject.
• Bounces go to cf-bounce.<domain>. Don't delete those DNS records.

References

• Cloudflare docs: https://developers.cloudflare.com/email-service/
• Get started: https://developers.cloudflare.com/email-service/get-started/send-emails/
• Email Routing (for inbound): https://developers.cloudflare.com/email-routing/