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v93

OpenAPI 3.1.0raw.githubusercontent.com2026-08-01218121759.7 KB
Transactional

Send transactional or marketing email

Queues an email for sending. The default emailType is transactional. Set it to marketing for a consented single-recipient lifecycle or promotional message. Marketing mode creates or links a minimal subscriber, honors unsubscribe suppression, adds the standard marketing footer, and emits RFC 8058 one-click-unsubscribe headers. The caller remains responsible for having consent or another lawful basis.

You can either:

  • Provide a canonical slug (or compatibility alias templateId) to use a saved template
  • Provide subject and canonical body (or compatibility alias html) to send custom content directly

If both a canonical field and its alias are provided, slug must match templateId and body must match html.

Recipients:

  • to can be a single email or an array of up to 50 emails
  • Duplicate emails are automatically deduplicated
  • Marketing mode requires exactly one to recipient and does not support cc or bcc

Attachments:

  • Attachments can be provided as Base64-encoded content or URLs
  • Maximum total attachment size: 40MB per email
  • Any file type supported (PDFs, images, documents, etc.)

A successful response means the email was accepted for background processing. Transactional emails are not blocked by subscriber unsubscribe or double opt-in status. If a recipient is suppressed because of a hard bounce or spam complaint, the worker records the send as suppressed instead of delivering it.

Optionally set from (domain must be verified) and replyTo addresses. When reply tracking is enabled, Sequenzy uses a unique trackable Reply-To header and treats the resolved reply destination as the forwarding destination for captured replies. When replyTo is omitted, direct-content sends inherit the company's default reply profile and saved-template sends prefer the template reply profile before the company default. Both fall back to the first company reply profile. The resolved destination is retained whether or not reply tracking is enabled; it is sent as the Reply-To header only when reply tracking is disabled. Variables can be passed to customize the email content. Nested objects and arrays are supported for repeat blocks, such as items. {{viewInBrowserUrl}} is generated automatically for a hosted copy link. For a single recipient, Sequenzy matches an existing subscriber by subscriberExternalId or email and backfills stored first and last names when the corresponding request variables are omitted; explicit variables take precedence. Returns immediately with a durable emailSendId and the accepted emailType. If Sequenzy detects likely missing or unused variables before queueing, the successful response includes a non-blocking diagnostics warning object. Missing values do not block queueing or sending; a required variable that is not provided and has no default renders as an empty string.

post/transactional/send

Request body

slugstring

Canonical slug of the transactional email template to use (mutually exclusive with direct content).

templateIdstring

Compatibility alias for slug. Despite the field name, pass the saved transactional email API slug, not its database ID. Must match slug when both are provided.

subscriberExternalIdstring

Customer-owned subscriber ID for single-recipient sends. If it matches an existing subscriber, analytics and localization use that subscriber; the value is also stored on the send and emitted as external_id in outbound email webhooks even when no subscriber exists. Maximum length is 255 characters.

emailType'transactional' | 'marketing'

Delivery policy. Marketing mode requires one recipient, creates or links a minimal subscriber, honors unsubscribe suppression, adds the standard footer, and emits RFC 8058 List-Unsubscribe and List-Unsubscribe-Post headers.

subjectstring

Email subject (required if not using slug)

bodystring

Canonical email body HTML content (required if not using a template slug).

htmlstring

Compatibility alias for body. Accepted with subject for direct sends and must match body when both are provided.

previewstring

Preview text for the email (only used with direct content)

variablesobject

Variables for template replacement (works with both modes). Values can be scalars, nested objects, or arrays used by repeat blocks. For a single recipient, stored subscriber first and last names fill missing name variables; explicit request variables take precedence. Raw HTML templates can use simple subscriber/custom-attribute conditionals such as {{#if subscriber.plan}}...{{else}}...{{/if}} and {{#unless subscriber.plan}}...{{/unless}}. Variables are always HTML-escaped; a template can prefix a tag with html. ({{html.prerenderedHtml}}) to insert a trusted HTML value unescaped. Injected HTML is sanitized (scripts, event handlers, and dangerous URLs are stripped), only applies in HTML text position, and must not contain end-user input. Likely variable issues are returned as non-blocking diagnostics when possible; missing required variables without defaults render as empty strings and do not block sending.

fromstring

Custom from address. Format: "Name <email>" or just "email". The domain must be verified for your account. If not verified, this field is silently ignored.

replyTostring

Reply-to address. Format: "Name <email>" or just "email". Can be any valid email address. When reply tracking is disabled, this value is sent as the email's Reply-To header. When reply tracking is enabled, Sequenzy sends a unique trackable Reply-To header and stores this value as the forwarding destination for replies. When omitted, direct-content sends inherit the company default and saved-template sends prefer the template reply profile before the company default. Both fall back to the first company reply profile. The resolved destination is retained whether or not reply tracking is enabled; it is sent directly only when reply tracking is disabled.

Example request

{
  "slug": "welcome-email",
  "templateId": "welcome-email",
  "subscriberExternalId": "user_123",
  "emailType": "marketing",
  "subject": "Welcome to our platform!",
  "body": "<h1>Welcome!</h1><p>Thanks for signing up.</p>",
  "html": "<h1>Welcome!</h1><p>Thanks for signing up.</p>",
  "preview": "Welcome to our platform",
  "variables": {
    "NAME": "John",
    "event": {
      "items": [
        {
          "title": "Pro plan",
          "description": "Monthly subscription"
        }
      ]
    }
  },
  "from": "Notifications <notifications@example.com>",
  "replyTo": "Support <support@example.com>",
  "attachments": [
    {
      "filename": "invoice.pdf",
      "path": "https://example.com/invoices/123.pdf"
    }
  ],
  "trackingSettings": {
    "clickTracking": false
  }
}

Response

Email queued successfully

OR

Example response

{
  "success": true,
  "emailSendId": "send_abc123",
  "jobId": "job_abc123",
  "diagnostics": {
    "status": "warning",
    "message": "Email was queued. A required variable is missing and will render as an empty string.",
    "missingRequiredVariables": [
      {
        "name": "RESET_URL",
        "lookupName": "reset_url",
        "message": "Email was queued. Required variable \"RESET_URL\" is missing and will render as an empty string.",
        "usedIn": [
          {
            "surface": "block",
            "field": "url",
            "blockId": "reset-button",
            "blockType": "button"
          }
        ],
        "suggestions": [
          "resetpasswordlink"
        ]
      }
    ],
    "unusedVariables": [
      {
        "name": "resetpasswordlink",
        "message": "Variable \"resetpasswordlink\" was provided but is not used by the email template.",
        "suggestions": [
          "reset_url"
        ]
      }
    ]
  }
}