Email Templates with Postmark
postmark-templates
Use when creating, managing, or sending with Postmark server-side email templates — Handlebars syntax, layout inheritance, template validation, and cross-server pushing.
SKILL.md
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Email Templates with Postmark
Overview
Postmark templates are server-side email templates using Handlebars syntax. Templates are rendered on Postmark's servers — no client-side rendering library needed.
| Feature | Description |
|---|---|
| Syntax | Handlebars (Mustache-compatible) |
| Rendering | Server-side — no React, no client library |
| Types | Standard templates and Layout templates |
| Inheritance | Standard templates can inherit from a Layout |
| Validation | API endpoint to test-render templates before sending |
| Cross-server | Push templates between servers (staging → production) |
| Limit | 100 templates per server (contact support for more) |
Quick Start
- Create a template via API or the Postmark dashboard
- Define variables using Handlebars syntax:
{{variable_name}} - Send with template using
POST /email/withTemplateorPOST /email/batchWithTemplates - Pass data via
TemplateModel— Postmark renders and sends
Template Syntax (Handlebars)
Hello {{name}}, {{! variable }}
{{{html_content}}} {{! unescaped HTML }}
{{#if premium}}Premium member{{/if}} {{! conditional }}
{{#each items}}{{this.name}}{{/each}} {{! iteration }}
{{customer.address.city}} {{! nested object }}
See references/handlebars-syntax.md for the full syntax reference including conditionals, iteration with index, nested objects, and common mistakes.
Template Types
| Type | TemplateType | Sendable | Purpose |
|---|---|---|---|
| Standard | "Standard" | Yes | Defines subject, HTML, and text body |
| Layout | "Layout" | No | Reusable wrapper injected via {{{@content}}} |
Standard templates can reference a Layout via LayoutTemplate: "layout-alias". The Standard template's body replaces {{{@content}}} in the Layout at send time.
See references/layout-templates.md for layout creation, assignment, and examples.
API Endpoints
Template CRUD
| Endpoint | Method | Description |
|---|---|---|
/templates | POST | Create a new template |
/templates | GET | List all templates (?count=100&offset=0&templateType=Standard) |
/templates/{idOrAlias} | GET | Get a single template |
/templates/{idOrAlias} | PUT | Update a template |
/templates/{idOrAlias} | DELETE | Delete a template |
/templates/validate | POST | Validate template rendering |
/templates/push | PUT | Push templates to another server |
Sending with Templates
| Endpoint | Method | Description |
|---|---|---|
/email/withTemplate | POST | Send single email with template |
/email/batchWithTemplates | POST | Send batch with templates (up to 500) |
Send with Template
Always use TemplateAlias over TemplateId — aliases survive re-creation and work across environments:
const postmark = require('postmark');
const client = new postmark.ServerClient(process.env.POSTMARK_SERVER_TOKEN);
await client.sendEmailWithTemplate({
From: '[email protected]',
To: '[email protected]',
TemplateAlias: 'welcome-email',
TemplateModel: {
name: 'Jane Doe',
product_name: 'Acme App'
},
MessageStream: 'outbound'
});
Validate a Template
Test-render without sending — useful in CI/CD before deploying template changes:
const validation = await client.validateTemplate({
Subject: 'Welcome {{name}}',
HtmlBody: '<h1>Hello {{name}}</h1>',
TextBody: 'Hello {{name}}',
TestRenderModel: { name: 'Test User' }
});
console.log('Valid:', validation.AllContentIsValid);
console.log('Rendered:', validation.Subject.RenderedContent);
See references/template-api.md for full CRUD operations (create, list, update, delete), batch sending, validate, and push between servers.
Common Mistakes
| Mistake | Fix |
|---|---|
Using {{html}} for HTML content | Use triple braces {{{html}}} for unescaped HTML |
Forgetting {{{@content}}} in Layout | Layout templates must include {{{@content}}} placeholder |
| Deleting a Layout with dependents | Remove layout association from Standard templates first |
| Using Template ID across environments | Use TemplateAlias — it survives re-creation and works across servers |
| Not validating before deploy | Use /templates/validate to test-render before sending |
| Sending a Layout directly | Layouts are wrappers — you can only send Standard templates |
| Missing TemplateModel fields | Handlebars renders missing variables as empty strings — validate your data |
| Exceeding 100 templates | Contact Postmark support to increase the per-server limit |
Notes
- Templates use Handlebars (Mustache-compatible) syntax — no React or client-side rendering needed
- Template aliases are strings; template IDs are integers — prefer aliases for portability
TemplateTypeis eitherStandard(sendable) orLayout(wrapper)- Layout inheritance: Standard template body replaces
{{{@content}}}in the Layout - Push templates between servers using the Account Token (not Server Token)
- Maximum 100 templates per server by default
- Template validation (
/templates/validate) lets you test-render without sending - Both
TemplateIdandTemplateAliaswork for sending — use one, not both