README

Easily integrate Lettermint into your Laravel application.

Requirements

• PHP 8.2 or higher
• Laravel 9 or higher

Installation

You can install the package via composer:

composer require lettermint/lettermint-laravel

You can publish the config file with:

php artisan vendor:publish --tag="lettermint-config"

This creates a config/lettermint.php file where you can add your project and API tokens.

Configuration

Setting your project token

Add your Lettermint project token in your .env file. This token is used for sending email through Laravel mail:

LETTERMINT_PROJECT_TOKEN=your-lettermint-project-token

The legacy LETTERMINT_TOKEN environment variable is still supported, but LETTERMINT_PROJECT_TOKEN is preferred for new applications.

Or update the config/lettermint.php file as needed.

Setting your API token

Add your Lettermint API token in your .env file when you want to use the Team API from your Laravel application:

LETTERMINT_API_TOKEN=your-lettermint-api-token

Setting the request timeout

The default Lettermint API request timeout is 15 seconds. You can override it in your .env file:

LETTERMINT_TIMEOUT=30

Add the transport

In your config/mail.php, set the default option to lettermint:

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

Add the service

In your config/services.php, add the Lettermint service:

    'lettermint' => [
        'token' => env('LETTERMINT_PROJECT_TOKEN', env('LETTERMINT_TOKEN')),
        'api_token' => env('LETTERMINT_API_TOKEN'),
    ],

Using the Team API

Resolve the PHP SDK API client from Laravel's container:

use Lettermint\Client\ApiClient;

$projects = app(ApiClient::class)->projects->list();
$team = app('lettermint.api')->team->retrieve();

Using Routes

If you would like to specify the Lettermint route that should be used by a given mailer, you may add the route_id configuration option to the mailer's configuration array in your config/mail.php file:

'lettermint' => [
    'transport' => 'lettermint',
    'route_id' => env('LETTERMINT_ROUTE_ID'),
],

Multiple mailers with different routes

You can configure multiple mailers using the same Lettermint transport but with different route IDs:

// config/mail.php
'mailers' => [
    'lettermint_marketing' => [
        'transport' => 'lettermint',
        'route_id' => env('LETTERMINT_MARKETING_ROUTE_ID'),
    ],
    'lettermint_transactional' => [
        'transport' => 'lettermint',
        'route_id' => env('LETTERMINT_TRANSACTIONAL_ROUTE_ID'),
    ],
],

Then use them in your application:

Mail::mailer('lettermint_marketing')->to($user)->send(new MarketingEmail());
Mail::mailer('lettermint_transactional')->to($user)->send(new TransactionalEmail());

Idempotency Support

The Lettermint Laravel driver prevents duplicate email sends by using idempotency keys. This is especially useful when emails are sent from queued jobs that might be retried.

Configuration Options

You can configure idempotency behavior per mailer in your config/mail.php:

'mailers' => [
    'lettermint' => [
        'transport' => 'lettermint',
        'idempotency' => true, // Enable automatic content-based idempotency
        'idempotency_window' => 86400, // Window in seconds (default: 24 hours)
    ],
    'lettermint_marketing' => [
        'transport' => 'lettermint',
        'route_id' => 'marketing',
        'idempotency' => false, // Disable automatic idempotency
    ],
],

Idempotency Options:

• idempotency: Enable/disable automatic content-based idempotency
  • true: Generates idempotency keys based on email content
  • false (default): Disables automatic idempotency (user headers still work)
• idempotency_window: Time window in seconds for deduplication
  • Default: 86400 (24 hours to match Lettermint API retention)
  • Set to match your needs (e.g., 3600 for 1 hour, 300 for 5 minutes)
  • When set to 86400 or higher, emails with identical content are permanently deduplicated within the API retention period

Automatic Idempotency

When idempotency is true, the driver generates a unique key based on:

• Email subject, recipients (to, cc, bcc), and content
• Sender address (to differentiate between different sending contexts)
• Time window (if less than 24 hours)

This ensures:

• Identical emails are only sent once within the configured time window
• Retried queue jobs won't create duplicate emails
• Different emails or the same email after the time window will be sent normally

Custom Idempotency Keys

You can override any configuration by setting a custom idempotency key in the email headers:

Mail::send('emails.welcome', $data, function ($message) {
    $message->to('user@example.com')
        ->subject('Welcome!')
        ->getHeaders()->addTextHeader('Idempotency-Key', 'welcome-user-123');
});

Priority order (highest to lowest):

1. Idempotency-Key header in the email (always respected, overrides any config)
2. Automatic Message-ID (if idempotency is true)
3. No idempotency (if idempotency is false)

Important: The idempotency: false configuration only disables automatic idempotency. User-provided Idempotency-Key headers are always respected, giving users full control on a per-email basis.

Tags and Metadata

The Lettermint Laravel driver supports adding tags and metadata to your emails for better organization, tracking, and analytics.

Using Tags

Tags help you categorize and filter your emails in the Lettermint dashboard. You can add tags using Laravel's native mailable methods:

Method 1: Using Laravel's tag() method (Recommended)

use App\Mail\WelcomeEmail;
use Illuminate\Support\Facades\Mail;

Mail::send((new WelcomeEmail($user))
    ->tag('onboarding')
);

Method 2: Using the envelope method in your Mailable

use Illuminate\Mail\Mailables\Envelope;

class WelcomeEmail extends Mailable
{
    public function envelope(): Envelope
    {
        return new Envelope(
            subject: 'Welcome to our platform!',
            tags: ['onboarding'], // Only one tag is allowed
        );
    }
}

Method 3: Using custom header (backward compatibility)

To minimise confusion with the way of tagging emails sent via the SMTP relay, the Lettermint Laravel driver also supports the X-LM-Tag header. This will be converted to the TagHeader envelope method automatically.

use Illuminate\Mail\Mailables\Headers;

class WelcomeEmail extends Mailable
{
    public function headers(): Headers
    {
        return new Headers(
            text: [
                'X-LM-Tag' => 'onboarding',
            ],
        );
    }
}

Using Metadata

Metadata allows you to attach custom key-value pairs to your emails for enhanced tracking and analytics:

Method 1: Using Laravel's metadata() method (Recommended)

Mail::send((new OrderConfirmation($order))
    ->metadata('order_id', $order->id)
    ->metadata('customer_id', $order->customer_id)
);

Method 2: Using the envelope method

public function envelope(): Envelope
{
    return new Envelope(
        subject: 'Order Confirmation',
        metadata: [
            'order_id' => $this->order->id,
            'customer_id' => $this->order->customer_id,
            'order_total' => $this->order->total,
        ],
    );
}

Combining Tags and Metadata

You can use both tags and metadata together:

Mail::send((new OrderShipped($order))
    ->tag('transactional')
    ->metadata('order_id', $order->id)
    ->metadata('tracking_number', $order->tracking_number)
);

Or in your mailable:

public function envelope(): Envelope
{
    return new Envelope(
        subject: 'Your order has shipped!',
        tags: ['transactional', 'shipping'],
        metadata: [
            'order_id' => $this->order->id,
            'tracking_number' => $this->order->tracking_number,
            'carrier' => $this->order->carrier,
        ],
    );
}

Note on Compatibility

• The driver supports Laravel's native tag() and metadata() methods (Laravel 9+)
• The X-LM-Tag header is supported for backward compatibility
• When both TagHeader and X-LM-Tag are present, the TagHeader takes precedence

Webhooks

The package provides built-in support for handling Lettermint webhooks with automatic signature verification.

Configuration

Add your webhook signing secret to your .env file:

LETTERMINT_WEBHOOK_SECRET=your-webhook-signing-secret

You can optionally configure the route prefix and timestamp tolerance:

LETTERMINT_WEBHOOK_PREFIX=lettermint
LETTERMINT_WEBHOOK_TOLERANCE=300

Or publish the config file and modify the webhooks section:

// config/lettermint.php
'webhooks' => [
    'secret' => env('LETTERMINT_WEBHOOK_SECRET'),
    'prefix' => env('LETTERMINT_WEBHOOK_PREFIX', 'lettermint'),
    'tolerance' => env('LETTERMINT_WEBHOOK_TOLERANCE', 300),
],

Webhook Endpoint

The package automatically registers a webhook endpoint at:

POST /{prefix}/webhook

By default, this is POST /lettermint/webhook. Configure this URL in your Lettermint dashboard.

Handling Webhook Events

The package dispatches Laravel events for each webhook type. Listen to specific events in your EventServiceProvider or using closures:

use Lettermint\Laravel\Events\MessageDelivered;
use Lettermint\Laravel\Events\MessageHardBounced;
use Lettermint\Laravel\Events\MessageSpamComplaint;

// In EventServiceProvider
protected $listen = [
    MessageDelivered::class => [
        HandleEmailDelivered::class,
    ],
    MessageHardBounced::class => [
        HandleEmailBounced::class,
    ],
];

// Or using closures
Event::listen(MessageDelivered::class, function (MessageDelivered $event) {
    Log::info('Email delivered', [
        'message_id' => $event->data->messageId,
        'recipient' => $event->data->recipient,
        'status_code' => $event->data->response->statusCode,
    ]);
});

Event::listen(MessageHardBounced::class, function (MessageHardBounced $event) {
    // Handle permanent bounce - consider disabling the recipient
    $recipient = $event->data->recipient;
    $reason = $event->data->response->content;
});

Available Events

Listening to All Events

You can listen to all webhook events using the base class:

use Lettermint\Laravel\Events\LettermintWebhookEvent;

Event::listen(LettermintWebhookEvent::class, function (LettermintWebhookEvent $event) {
    Log::info('Webhook received', [
        'type' => $event->getEnvelope()->event->value,
        'id' => $event->getEnvelope()->id,
    ]);
});

Event Structure

Each event has two main properties:

• $event->envelope - Common webhook envelope (id, event type, timestamp)
• $event->data - Event-specific typed payload

// Envelope (common to all events)
$event->envelope->id;        // Webhook event ID (string)
$event->envelope->event;     // WebhookEventType enum
$event->envelope->timestamp; // DateTimeImmutable

// Data (typed per event)
// For MessageDelivered:
$event->data->messageId;              // string
$event->data->recipient;              // string
$event->data->response->statusCode;   // int
$event->data->response->content;      // string|null
$event->data->metadata;               // array
$event->data->tag;                    // string|null

Typed Event Data

Each event type has its own typed data class:

Helper Methods

The WebhookEventType enum provides helper methods:

$event->envelope->event->isBounce();        // true for hard/soft bounces
$event->envelope->event->isDeliveryIssue(); // true for bounces, failed, suppressed

Testing

composer test

Changelog

Please see CHANGELOG for more information on what has changed recently.

Contributing

Please see CONTRIBUTING for details.

Security Vulnerabilities

Please review our security policy on how to report security vulnerabilities.

Credits

• Bjarn Bronsveld
• All Contributors

License

The MIT License (MIT). Please see License File for more information.