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This page provides a comprehensive reference for all configuration options available in the Lettermint Laravel package.

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Package Configuration

The package configuration is located in config/lettermint.php. Publish it using: 
php artisan vendor:publish --tag=lettermint-config

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API Token

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token
string
required
Your Lettermint API token. Every Lettermint project has a unique API token that can be found in your project settings.Environment Variable: LETTERMINT_TOKEN
'token' => env('LETTERMINT_TOKEN'),
Alternatively, you can configure the token in config/services.php:
'services' => [
    'lettermint' => [
        'token' => env('LETTERMINT_TOKEN'),
    ],
],

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Webhook Configuration

All webhook-related settings are nested under the webhooks key.
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webhooks.secret
string
required
The signing secret used to verify incoming webhook requests from Lettermint. This ensures that the webhook payload is authentic and hasn’t been tampered with.Environment Variable: LETTERMINT_WEBHOOK_SECRETDefault: null
'secret' => env('LETTERMINT_WEBHOOK_SECRET'),
Find your webhook signing secret in your Lettermint project settings under the Webhooks section.
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webhooks.prefix
string
The route prefix for the webhook endpoint. The full webhook URL will be constructed as {your-app-url}/{prefix}/webhook.Environment Variable: LETTERMINT_WEBHOOK_PREFIXDefault: lettermint
'prefix' => env('LETTERMINT_WEBHOOK_PREFIX', 'lettermint'),
Example URLs:
  • Default: https://yourapp.com/lettermint/webhook
  • Custom prefix api/events: https://yourapp.com/api/events/webhook
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webhooks.tolerance
integer
The maximum allowed time difference (in seconds) between the webhook timestamp and the current server time. This helps prevent replay attacks.Environment Variable: LETTERMINT_WEBHOOK_TOLERANCEDefault: 300 (5 minutes)
'tolerance' => env('LETTERMINT_WEBHOOK_TOLERANCE', 300),
If the timestamp difference exceeds this value, the webhook request will be rejected.

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Mail Transport Configuration

Configure the Lettermint mail transport in config/mail.php to send emails using Laravel’s Mail facade.

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Basic Setup

'mailers' => [
    'lettermint' => [
        'transport' => 'lettermint',
    ],
],

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Transport Options

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route_id
string
The Lettermint route ID to use for sending emails through this mailer. When specified, all emails sent through this mailer will use the specified route.
'mailers' => [
    'lettermint' => [
        'transport' => 'lettermint',
        'route_id' => 'route_abc123',
    ],
],
This is useful when you have multiple sending routes configured in Lettermint and want to assign specific mailers to specific routes.
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idempotency
boolean
Enable automatic idempotency key generation for emails sent through this mailer. When enabled, the package automatically generates a stable idempotency key based on email content.Default: false
'mailers' => [
    'lettermint' => [
        'transport' => 'lettermint',
        'idempotency' => true,
    ],
],
The idempotency key is generated using a SHA256 hash of:
  • Email subject
  • Recipients (to, cc, bcc)
  • Email body (HTML or text)
  • Sender address
  • Timestamp (if window is less than 24 hours)
This ensures that retrying the same email (e.g., from a failed queue job) won’t result in duplicate sends.
Individual emails can override this by setting a custom Idempotency-Key header, which takes precedence over automatic generation.
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idempotency_window
integer
The time window (in seconds) for automatic idempotency key generation. This option is only used when idempotency is enabled.Default: 86400 (24 hours)
'mailers' => [
    'lettermint' => [
        'transport' => 'lettermint',
        'idempotency' => true,
        'idempotency_window' => 3600, // 1 hour
    ],
],
How it works:
  • 24 hours (default): The idempotency key remains the same for the same email content indefinitely, matching Lettermint’s API retention period. This provides permanent deduplication.
  • Less than 24 hours: The current timestamp (rounded to the window) is included in the key generation. This allows the same email to be sent again after the window expires.
Example use cases:
WindowUse Case
86400 (24h)Prevent duplicate sends permanently (useful for transactional emails)
3600 (1h)Allow resending the same email after 1 hour (useful for notifications)
300 (5m)Short-term retry protection for queue failures

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Configuration Examples

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Basic Configuration

config/lettermint.php: 
return [
    'token' => env('LETTERMINT_TOKEN'),
    'webhooks' => [
        'secret' => env('LETTERMINT_WEBHOOK_SECRET'),
        'prefix' => 'lettermint',
        'tolerance' => 300,
    ],
];
.env: 
LETTERMINT_TOKEN=your_api_token_here
LETTERMINT_WEBHOOK_SECRET=your_webhook_secret_here

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Multiple Mailers with Different Routes

config/mail.php: 
'mailers' => [
    // Transactional emails with idempotency
    'transactional' => [
        'transport' => 'lettermint',
        'route_id' => 'route_transactional',
        'idempotency' => true,
        'idempotency_window' => 86400, // 24 hours
    ],
    
    // Marketing emails without idempotency
    'marketing' => [
        'transport' => 'lettermint',
        'route_id' => 'route_marketing',
        'idempotency' => false,
    ],
    
    // Notification emails with short retry window
    'notifications' => [
        'transport' => 'lettermint',
        'route_id' => 'route_notifications',
        'idempotency' => true,
        'idempotency_window' => 3600, // 1 hour
    ],
],

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Custom Webhook Endpoint

config/lettermint.php: 
return [
    'token' => env('LETTERMINT_TOKEN'),
    'webhooks' => [
        'secret' => env('LETTERMINT_WEBHOOK_SECRET'),
        'prefix' => 'api/webhooks/lettermint',
        'tolerance' => 600, // 10 minutes
    ],
];
This configures the webhook endpoint at https://yourapp.com/api/webhooks/lettermint/webhook.

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