Templates

Create reusable, dynamic email templates with Handlebars syntax. Templates support conditionals, loops, and partials.

Creating a Template

Templates are created in the PostaSend dashboard under Templates, or programmatically via the API. Each template has a unique ID (e.g. tmpl_welcome_v1) and supports Handlebars syntax for dynamic content. Templates can include an HTML body, plain text fallback, and a subject line — all of which support variable interpolation.

typescript
const template = await client.templates.create({
  name: 'welcome-email-v1',
  subject: 'Welcome to {{appName}}, {{firstName}}!',
  html: `
    <h1>Welcome, {{firstName}}!</h1>
    <p>Your {{plan}} plan is now active.</p>
    {{#if trialDays}}
      <p>You have {{trialDays}} days left in your free trial.</p>
    {{/if}}
    <a href="{{dashboardUrl}}">Go to dashboard</a>
  `,
  text: 'Welcome, {{firstName}}! Your {{plan}} plan is now active.',
});

console.log(template.id); // 'tmpl_abc123'

Sending with a Template

To send an email using a template, pass the templateId and a data object containing the values for your template variables. PostaSend validates that all required variables are present before queuing the email.

typescript
await client.emails.send({
  from: 'hello@yourdomain.com',
  to: ['newuser@example.com'],
  templateId: 'tmpl_abc123',
  data: {
    firstName: 'Alice',
    appName: 'Acme',
    plan: 'Growth',
    trialDays: 14,
    dashboardUrl: 'https://app.acme.com/dashboard',
  },
});

Template Versioning

Every time you update a template, PostaSend creates a new version. By default, sends use the latest published version. You can pin a send to a specific version by passing templateVersion alongside templateId. This is useful for A/B testing or rolling back a bad template change.

typescript
// Send with specific version
await client.emails.send({
  from: 'hello@yourdomain.com',
  to: ['user@example.com'],
  templateId: 'tmpl_abc123',
  templateVersion: 3,
  data: { firstName: 'Alice' },
});

// List template versions
const versions = await client.templates.versions('tmpl_abc123');
// [{ version: 4, publishedAt: ..., status: 'published' }, ...]

Previewing Templates

Preview a rendered template with sample data before sending. The preview API returns the fully rendered HTML and text, making it easy to build a preview UI in your dashboard.

typescript
const preview = await client.templates.preview('tmpl_abc123', {
  data: {
    firstName: 'Preview User',
    appName: 'Acme',
    plan: 'Starter',
    dashboardUrl: 'https://app.acme.com',
  },
});

console.log(preview.html); // fully rendered HTML string
console.log(preview.text); // fully rendered text string
console.log(preview.subject); // 'Welcome to Acme, Preview User!'
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