Skip to content

MailerPreviewEmail

POST mailer/email/preview

Assembles the message without sending anything: the subject, the final HTML, the generated text part, the headers, the size in bytes, and which placeholders stayed unresolved.

This is the method behind the template editor. It runs the same assembly path as sending, so what the editor shows is what the recipient would get.

Access Control

Allowed roles: admin, leader, manager.

Request

POST https://{broker_domain}/mailer/email/preview
{
  "templateId": 4,
  "data": {
    "name": "John",
    "amount": "250 EUR"
  },
  "to": "[email protected]"
}

{
  "command": "MailerPreviewEmail",
  "extID": "1",
  "data": {
    "templateId": 4,
    "data": {
      "name": "John",
      "amount": "250 EUR"
    },
    "to": "[email protected]"
  }
}

const res = await platform.MailerPreviewEmail({
  templateId: 4,
  data: {
    name: "John",
    amount: "250 EUR"
  },
  to: "[email protected]"
});

Request Data

Field Type Required Description
templateId int No Template to render; use it instead of passing content
subject string No Subject, up to 512 characters
html string No HTML body
text string No Plain-text part; generated from the HTML when omitted
structure array No Email builder tree; the HTML is rendered from it
data object No Placeholder values
to string No Recipient, to render the unsubscribe link
kind enum No TRANSACTIONAL or MARKETING

Behavior

  • Without to a marketing preview cannot build a real unsubscribe link — the response says so with unsubscribePending: true instead of failing.
  • bytes is what decides whether Gmail will clip the email; see MailerLintEmail for the full pre-send check.

Response Data

{
  "subject": "John, your deposit of 250 EUR is confirmed",
  "html": "<!doctype html><html>…</html>",
  "text": "John, your deposit of 250 EUR is confirmed",
  "kind": "MARKETING",
  "headers": {
    "List-Unsubscribe": "<https://brand.example/unsubscribe?token=…>",
    "List-Unsubscribe-Post": "List-Unsubscribe=One-Click"
  },
  "unsubscribePending": false,
  "bytes": 18422,
  "placeholders": ["name", "amount"],
  "missingPlaceholders": [],
  "templateId": 4
}

Errors

Code Error Description
400 VALIDATION_ERROR No content and no template
404 TEMPLATE_NOT_FOUND Template not found in the brand