Email

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://raw.githubusercontent.com/api-evangelist/customer-io/main/json-schema/customer-io-update-email-content-schema.json",
  "title": "Email",
  "description": "Update the contents of an email newsletter variant. You can set the sender with `from_id`. If you don't provide it, the existing sender is preserved.\n",
  "x-generated": "2026-10-12",
  "x-method": "derived",
  "x-generator": "derive-json-schema.py",
  "x-source": "openapi/customer-io-newsletter-variants-api-openapi.yml#/components/schemas/updateEmailContent",
  "allOf": [
    {
      "type": "object",
      "properties": {
        "type": {
          "x-scalar-ignore": true,
          "description": "Channel type for a newsletter or newsletter content variant.",
          "type": "string",
          "enum": [
            "email",
            "webhook",
            "twilio",
            "push",
            "in_app",
            "inbox"
          ],
          "readOnly": true
        },
        "deduplicate_id": {
          "x-scalar-ignore": true,
          "type": "string",
          "readOnly": true,
          "description": "An identifier in the format `id:timestamp` where the id is for the object you're working with (Campaigns, Deliveries, Exports, Identities, Newsletters, Segments, and Templates), and the timestamp is the last time the object was updated."
        }
      }
    },
    {
      "type": "object",
      "properties": {
        "type": {
          "type": "string",
          "enum": [
            "email"
          ],
          "readOnly": true
        },
        "body": {
          "type": "string",
          "description": "The HTML body of the email. You cannot modify the body if you created the newsletter with Design Studio or the drag-and-drop editor."
        },
        "body_amp": {
          "x-scalar-ignore": true,
          "type": "string",
          "description": "AMP-enabled content for your email. If a recipient's email client doesn't support AMP, they receive your `body` content instead. Make sure you're [set up to send AMP](/journeys/channels/email/layouts/amp-for-email/) first."
        },
        "body_plain": {
          "x-scalar-ignore": true,
          "type": "string",
          "description": "By default, your workspace generates a plaintext version of your message body for each delivery. Use this key to override the default plain text body."
        },
        "subject": {
          "x-scalar-ignore": true,
          "type": "string",
          "description": "The subject line for an `email` action."
        },
        "preheader_text": {
          "x-scalar-ignore": true,
          "type": "string",
          "description": "[Also known as \"preview text\"](/journeys/channels/email/headers/custom-preheader-text/), this is the small block of text shown in an email inbox next to or underneath the subject line.\n"
        },
        "from_id": {
          "x-scalar-ignore": true,
          "type": "integer",
          "description": "The identifier of the `from` address, commonly known as the \"sender\". Use [List sender identities](#tag/sender-identities/listSenders) to find valid IDs."
        },
        "reply_to_id": {
          "x-scalar-ignore": true,
          "type": [
            "integer",
            "null"
          ],
          "description": "The identifier for the `reply_to` address, if applicable. Use [List sender identities](#tag/sender-identities/listSenders) to find valid IDs."
        },
        "recipient": {
          "type": "string",
          "description": "The recipient address for the newsletter. By default, it's `{{customer.email}}`."
        }
      }
    }
  ]
}