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Projects and folders help you organize your email templates. Use projects to separate templates by brand, product, or team, and use folders within projects to group related templates together.

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Overview

The template hierarchy in Lettr works as follows: 
Team
└── Project (e.g., "Marketing Site")
    ├── Folder (e.g., "Transactional")
    │   ├── Template: welcome-email
    │   ├── Template: password-reset
    │   └── Template: order-confirmation
    └── Folder (e.g., "Newsletters")
        ├── Template: weekly-digest
        └── Template: product-updates
Every team has a default project created automatically. Templates are organized into projects and folders, which you can reference when working with the API.

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Using Projects in API Calls

When sending emails with templates, you can specify which project to use: 
await lettr.emails.send({
  from: 'you@example.com',
  to: ['recipient@example.com'],
  subject: 'Welcome',
  template_slug: 'welcome-email',
  project_id: 123
});
If you don’t specify a project_id, Lettr uses the default project for your team.

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Listing Templates by Project

When retrieving templates via API, templates are returned with their project context: 
curl -X GET "https://app.lettr.com/api/templates" \
  -H "Authorization: Bearer lttr_xxxxxxxxxxxx"
Response includes project information: 
{
  "data": [
    {
      "id": 1,
      "name": "Welcome Email",
      "slug": "welcome-email",
      "project_id": 123,
      "folder_id": 3,
      "created_at": "2026-01-10T09:00:00Z",
      "updated_at": "2026-01-15T14:30:00Z"
    },
    {
      "id": 2,
      "name": "Order Confirmation",
      "slug": "order-confirmation",
      "project_id": 123,
      "folder_id": 5,
      "created_at": "2026-01-12T11:00:00Z",
      "updated_at": "2026-01-20T08:15:00Z"
    }
  ]
}
You can scope both endpoints to a specific project by adding ?project_id=123. If omitted, your team’s default project is used.

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Default Project

Every team has a default project. This project:
  • Cannot be deleted
  • Receives templates when no project is specified
  • Is used when API calls don’t include a project_id

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Best Practices

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Project Organization

  • By Brand: Create separate projects for each brand if you send emails from multiple brands
  • By Product: Separate projects for different products or services
  • By Environment: Consider separate projects for production vs. staging if testing extensively

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Folder Organization

  • By Email Type: Group transactional, marketing, and notification emails
  • By Customer Journey: Organize by lifecycle stage (onboarding, engagement, retention)
  • By Frequency: Separate one-time emails from recurring ones

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Naming Conventions

Use consistent naming patterns: 
Projects:
- "Acme SaaS"
- "Acme Enterprise"
- "Internal Communications"

Folders:
- "Transactional"
- "Onboarding Sequence"
- "Product Updates"

Templates (slugs):
- welcome-email
- password-reset
- weekly-digest-v2

Template Editor

Create templates with the visual editor

Templates Introduction

Get started with email templates

Template Versions

Manage multiple versions of templates

Storage Domains

Configure custom domains for template assets