# Project Limits

By default, all verified domains are available to every project within your team. Project limits allow you to restrict a domain so that only specific projects can send emails from it.

## When to Use Project Limits

Project limits are useful when you need to enforce boundaries between different parts of your organization:

| Use Case | Example |
|----------|---------|
| **Multi-brand separation** | Restrict `mail.brand-a.com` to only the Brand A project |
| **Environment isolation** | Prevent staging projects from accidentally using production domains |
| **Security boundaries** | Limit sensitive domains to specific applications |

:::info
If all your projects share the same domains, you don't need to configure project limits—the default unrestricted behavior works well for most teams.
:::

## How It Works

Domains can be in one of two states:

| State | Description |
|-------|-------------|
| **Unrestricted** | Domain can be used by any project in your team (default) |
| **Restricted** | Domain can only be used by explicitly selected projects |

When a project attempts to send an email using a restricted domain it doesn't have access to, the API returns an error:

```json
{
  "message": "The domain 'mail.acme.com' is not available for use by this project."
}
```

## Configuring Project Limits

You can configure which projects have access to a domain from the domain settings page.

<Frame>
  ![Domain project limits configuration](/docs/images/domains/project-limits.png)
</Frame>

### Restricting a Domain

1. Navigate to [Domains](https://dash.lettermint.co/domains) in your dashboard
2. Click on the domain you want to restrict
3. In the project limits section, select the projects that should have access
4. Save your changes

### Removing Restrictions

To make a domain available to all projects again, simply remove all project selections. An empty selection means the domain is unrestricted and available to all projects in your team.

## Managing via API

You can manage project limits programmatically using the [Team API](/platform/teams/team-api/introduction).

### Restrict a Domain to Specific Projects

<CodeTabs>

```bash title="cURL"
curl -X PUT "https://api.lettermint.co/v1/domains/{domainId}/projects" \
  -H "Accept: application/json" \
  -H "Authorization: Bearer YOUR_TEAM_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "project_ids": ["project-uuid-1", "project-uuid-2"]
  }'
```

```javascript title="Node.js"
const response = await fetch(
  `https://api.lettermint.co/v1/domains/${domainId}/projects`,
  {
    method: 'PUT',
    headers: {
      'Accept': 'application/json',
      'Authorization': 'Bearer YOUR_TEAM_TOKEN',
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      project_ids: ['project-uuid-1', 'project-uuid-2']
    })
  }
);
const domain = await response.json();
```

```php title="PHP"
<?php
$curl = curl_init();
curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.lettermint.co/v1/domains/{$domainId}/projects",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_CUSTOMREQUEST => 'PUT',
  CURLOPT_HTTPHEADER => [
    'Accept: application/json',
    'Authorization: Bearer YOUR_TEAM_TOKEN',
    'Content-Type: application/json'
  ],
  CURLOPT_POSTFIELDS => json_encode([
    'project_ids' => ['project-uuid-1', 'project-uuid-2']
  ])
]);
$response = curl_exec($curl);
curl_close($curl);
```

</CodeTabs>

### Remove All Restrictions

Pass an empty array to make the domain available to all projects:

<CodeTabs>

```bash title="cURL"
curl -X PUT "https://api.lettermint.co/v1/domains/{domainId}/projects" \
  -H "Accept: application/json" \
  -H "Authorization: Bearer YOUR_TEAM_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "project_ids": []
  }'
```

```javascript title="Node.js"
const response = await fetch(
  `https://api.lettermint.co/v1/domains/${domainId}/projects`,
  {
    method: 'PUT',
    headers: {
      'Accept': 'application/json',
      'Authorization': 'Bearer YOUR_TEAM_TOKEN',
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      project_ids: []
    })
  }
);
```

```php title="PHP"
<?php
$curl = curl_init();
curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.lettermint.co/v1/domains/{$domainId}/projects",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_CUSTOMREQUEST => 'PUT',
  CURLOPT_HTTPHEADER => [
    'Accept: application/json',
    'Authorization: Bearer YOUR_TEAM_TOKEN',
    'Content-Type: application/json'
  ],
  CURLOPT_POSTFIELDS => json_encode([
    'project_ids' => []
  ])
]);
$response = curl_exec($curl);
curl_close($curl);
```

</CodeTabs>

**Success Response:**
```json
{
  "data": {
    "id": "domain-uuid",
    "domain": "mail.acme.com",
    "verified_at": "2024-01-15T10:30:00.000Z"
  },
  "message": "Domain projects updated successfully."
}
```

See the [Update Domain Projects](/api-reference/team/domain/update-projects-associated-with-a-domain) endpoint for the full API reference.

## Access Control

When a domain is restricted to specific projects, it affects who can manage the domain:

| Role | Can Edit Domain? |
|------|------------------|
| **Team Owner** | Always |
| **Team Member** | Only if they have access to at least one of the restricted projects |

:::warning
Team members who don't have access to any of the restricted projects will see the domain in the list but cannot modify its settings.
:::

## Troubleshooting

  <details>
<summary>Why can't I edit this domain?</summary>

The domain is restricted to projects you don't have access to. Contact your team owner to either:
    - Grant you access to one of the restricted projects, or
    - Add a project you have access to in the domain's project limits
  
</details>
  <details>
<summary>How do I make a domain available to all projects again?</summary>

Remove all project selections in the dashboard, or via API, set `project_ids` to an empty array `[]`.
  
</details>
  <details>
<summary>Can I restrict a domain to zero projects?</summary>

No. An empty project list means the domain is **unrestricted** and available to all projects. To completely disable a domain, you would need to delete it instead.
  
</details>

## Related

- [Projects and Routes](/platform/projects-and-routes/introduction) — Understand the team → project → route hierarchy
- [Team API Introduction](/platform/teams/team-api/introduction) — Manage team resources programmatically