The Email platform API covers two areas: sender identity (channels and domain verification) and message sends (action-based and subscription email via POST /v1/messages).

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Sending email

All email messages use the shared send endpoint: 
POST /v1/messages
The channel_id in the request body selects the verified sender identity. The message_type controls billing and delivery rules.
Message typeUseBilling unit
MESSAGEAction-based sends — receipts, confirmations, password resetsBasic Message
NEWSLETTERSubscription sends — newsletters, promotions to opted-in contactsBasic Message
Email has its own independent volume tiers. Tier thresholds and pricing are visible in your dashboard.

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Sender channels

Email channels define the sender address, verified domain, reply-to address, and which message types are permitted. Channels are managed in the dashboard.
ConceptDetail
channel_idEmail channel identifier (ch_ prefix). Required on every send. See Identifiers.
Sender domainDomain you have verified with SPF, DKIM, and DMARC records.
message_type allowlistEach channel is configured to allow MESSAGE, NEWSLETTER, or both.

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Deliverability

The platform enforces the following automatically:
  • Suppression lists — bounced, complained, and unsubscribed addresses are blocked from receiving future sends.
  • Unsubscribe headers — List-Unsubscribe and List-Unsubscribe-Post headers are added to all NEWSLETTER sends.
  • Bounce handling — hard bounces set the contact status to BOUNCED and suppress the address.

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Provider events → webhooks

Delivery events from the email provider are normalised and forwarded as Arowana webhook events. Email events use the email.* prefix — not message.*.
EventWhen
email.deliveredSMTP acceptance confirmed
email.bouncedHard or soft bounce received
email.openedOpen pixel fired (requires HTML content)
email.clickedLink click tracked
email.complainedSpam complaint received
email.unsubscribedOne-click unsubscribe processed
Subscribe to email.delivered, not message.delivered, when tracking email delivery. The event names are different by design — an endpoint subscribed to message.delivered will not receive email delivery updates.
See the Email webhook events for full payload reference.

Action-based email

Field reference for message_type: MESSAGE.

Subscription email

Field reference for message_type: NEWSLETTER.