Subscription email covers opted-in, list-based sends — campaigns, newsletters, announcements, promotional content. Uses channel type EMAIL with message_type: NEWSLETTER. Billed as Basic Message, identical to action-based email. Unlike RCS newsletter, there is no MAU charge for email subscription sends.
Subscription sends require valid GRANTED consent for the recipient and pass through suppression checks (bounced addresses, unsubscribes) before accept. Sends that fail these checks return 422.

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Request

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Authorization
string
required
Bearer <api_key>
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Idempotency-Key
string
UUID to prevent duplicate sends on retry.

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Body

{
  "channel_id": "ch_550e8400e29b41d4a716446655440000",
  "to": "subscriber@arowana.app",
  "subject": "This week at Example Co",
  "message_type": "NEWSLETTER",
  "content": {
    "html": "<html><body><h1>Weekly update</h1><p>Here's what's new...</p></body></html>",
    "text": "Weekly update — here's what's new..."
  }
}
​
channel_id
string
required
Email channel id configured for NEWSLETTER traffic.
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to
string
required
Recipient email. Checked against suppression lists and consent records before accept.
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subject
string
required
Email subject line.
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message_type
string
required
NEWSLETTER for subscription sends.
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content.html
string
HTML body. One-click unsubscribe is injected automatically where required by policy.
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content.text
string
Plain text fallback.
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template_id
string
Template reference instead of inline content. See Email action-based for template field details.

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Responses

{
  "message_id": "msg_f3a4b5c6",
  "status": "queued",
  "created_at": "2026-03-28T09:00:00Z",
  "billing": {
    "channel": "EMAIL",
    "message_type": "basic_message",
    "hold_amount": 0.09,
    "message_price": 0.09,
    "balance": {
      "free": 49.91,
      "reserved": 0.09,
      "total": 50.00
    },
    "tier": {
      "channel": "EMAIL",
      "current": "tier_1",
      "volume_used": 8420
    }
  }
}
​
message_id
string
Message id for status, revoke, and webhook correlation.
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billing.message_type
string
Always basic_message for email subscription sends. No MAU charge.
​
billing.tier
object