README

Official PHP SDK for the Mailer REST API v1. It wraps the transactional send, contacts, lists, tags, templates, messages and campaigns endpoints behind typed resources and readonly DTOs, with first-class error handling and idempotency support — plus an optional, batteries-included Laravel integration.

🤖 Integrating with an AI agent? Start with AGENTS.md — a terse, imperative integration playbook with the human-gate steps called out. This README is the full human reference.

Features

Typed resources + readonly DTOs over the full Mailer API v1 surface (send, contacts, lists, tags, templates, messages, read-only campaigns).
A precise exception hierarchy with machine code branching.
Automatic, idempotency-safe retries with exponential backoff.
Lazy pagination via cursor() generators (no page bookkeeping).
Per-send idempotency keys to make retries duplicate-free.
Optional Laravel integration (auto-discovered): a mailer mail transport, a mailer notification channel and a Mailer facade.
Zero required dependencies beyond Guzzle; the core works in plain PHP without any Illuminate package installed.

Requirements

PHP >= 8.2
guzzlehttp/guzzle ^7 (the only runtime dependency)
Laravel ^11.0 || ^12.0 || ^13.0 — optional, only for the Laravel integration (mail transport, notification channel, facade). The core SDK runs fine without it.

Installation

The package is published on Packagist — require it directly with Composer, no repository entry or Git/SSH access needed:

composer require mosaiqo/mailer-php:^1.1

Path repository (monorepo development)

When developing inside the Mailer monorepo, point Composer at the package directory with a path repository:

{
    "repositories": [
        { "type": "path", "url": "sdk/php" }
    ],
    "require": {
        "mosaiqo/mailer-php": "*"
    }
}

composer require mosaiqo/mailer-php

Quick start: integrate into a Laravel app

The full, copy-pasteable recipe to route a real Laravel app's email through a mailer-app instance. (Detailed behavior and options are documented further down.)

1. Require the package (published on Packagist):

composer require mosaiqo/mailer-php:^1.1

2. Set the environment variables.

# Route Laravel's Mail facade through the platform /send API
MAIL_MAILER=mailer

# Connection (both are REQUIRED — there is no default; a missing/placeholder
# value throws a MailerConfigurationException at boot instead of silently
# sending to a dead host)
MAILER_BASE_URL=https://<your-mailer-app-host>/api/v1
MAILER_API_TOKEN=<your-project-API-key>

Where to get the API key. In mailer-app, open Settings → API keys for the project you want to send from and create a key (it is shown once — copy it straight into MAILER_API_TOKEN). Keys are per project, so the key also selects which project's sender, templates and contacts the sends use.

3. Add the mailer mailer to config/mail.php.

'mailers' => [
    // ...existing mailers...
    'mailer' => [
        'transport' => 'mailer',
    ],
],

4. Send. Nothing else in your mailing code changes:

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

// A Mailable through the transport (MAIL_MAILER=mailer)
Mail::to('jane@example.com')->send(new WelcomeMail($user));

// A plain message
Mail::raw('Hello world', fn ($m) => $m->to('jane@example.com')->subject('Hi'));

Or call the API client directly — e.g. to render a stored template by slug with per-recipient variables:

use Mailer\Sdk\Laravel\Facades\Mailer;

Mailer::send()->email([
    'to' => 'jane@example.com',
    'template' => 'welcome',           // template slug from mailer-app
    'variables' => ['first_name' => 'Jane'],
]);

// ...or fully inline content
Mailer::send()->email([
    'to' => 'jane@example.com',
    'subject' => 'Welcome aboard',
    'body' => '<p>Hi {{ contact.first_name }}!</p>',
    'text' => 'Hi!',
]);

That is the whole integration. The rest of this document covers the SDK's full surface and the transport's detailed behavior.

Plain PHP usage

use Mailer\Sdk\MailerClient;

$client = new MailerClient(
    baseUrl: 'https://app.example.com/api/v1',
    token: 'your-project-api-key',
);

// Send a single transactional email (inline content)
$sent = $client->send()->email([
    'to' => 'jane@example.com',
    'subject' => 'Welcome aboard',
    'body' => '<p>Hi {{ contact.first_name }}!</p>',
    'text' => 'Hi!',
    'variables' => ['plan' => 'pro'],
]);

echo $sent->id;      // "11111111-2222-..."
echo $sent->status;  // "queued"

// Or send using a stored template by slug
$client->send()->email([
    'to' => 'jane@example.com',
    'template' => 'welcome',
    'variables' => ['first_name' => 'Jane'],
]);

Batch sends

$result = $client->send()->batch([
    ['to' => 'a@example.com', 'template' => 'welcome'],
    ['to' => 'b@example.com', 'subject' => 'Hi', 'body' => '<p>Hello</p>'],
]);

echo $result->queued; // 2
echo $result->failed; // 0

foreach ($result->messages as $item) {
    // $item->index, $item->status (queued|suppressed|failed), $item->id, $item->code, $item->error
}

Idempotency

email() and batch() accept a named idempotencyKey argument, sent as the Idempotency-Key header. Re-sending with the same key returns the original result instead of creating a duplicate (a conflicting reuse raises a ValidationException with code idempotency_conflict).

$client->send()->email(
    ['to' => 'jane@example.com', 'template' => 'welcome'],
    idempotencyKey: 'order-1234-welcome',
);

$client->send()->batch($messages, idempotencyKey: 'nightly-digest-2026-06-12');

Other resources

// Track an event
$client->send()->track('order.placed', 'jane@example.com', ['total' => 4200]);

// Subscribe a contact (double opt-in aware)
$client->send()->subscribe([
    'email' => 'jane@example.com',
    'first_name' => 'Jane',
    'lists' => [7],
    'tags' => ['newsletter'],
]);

// Contacts
$page = $client->contacts()->list(['status' => 'subscribed', 'per_page' => 50]);
$contact = $client->contacts()->get('jane@example.com');
$client->contacts()->update('jane@example.com', ['first_name' => 'Janet']);
$client->contacts()->tags('jane@example.com', add: ['vip'], remove: ['trial']);
$client->contacts()->cancelAutomationRuns('jane@example.com', automation: 12);
$client->contacts()->delete('jane@example.com'); // GDPR erase

// Lists
$lists = $client->lists()->list();
$list = $client->lists()->create('Newsletter', 'Weekly digest');
$client->lists()->attachContact($list->id, 'jane@example.com');
$client->lists()->detachContact($list->id, 'jane@example.com');

// Tags (flat array)
$tags = $client->tags()->list();

// Templates
$templates = $client->templates()->list();
$template = $client->templates()->create([
    'name' => 'Welcome',
    'slug' => 'welcome',
    'subject' => 'Welcome!',
    'body_html' => '<p>Hi</p>',
]);
$client->templates()->putVariant('welcome', 'es', [
    'subject' => '¡Bienvenido!',
    'body_html' => '<p>Hola</p>',
]);

// Messages (read-only)
$messages = $client->messages()->list(['status' => 'delivered']);
$message = $client->messages()->get('11111111-2222-...');
foreach ($message->events as $event) {
    // $event->type, $event->payload, $event->occurredAt
}

// Campaigns (read-only by design — no send/schedule from the SDK)
$campaigns = $client->campaigns()->list(['per_page' => 50]);
$campaign = $client->campaigns()->get(7);
// $campaign->stats is a populated CampaignStats only on get():
echo $campaign->stats->openRate ?? 0; // rates are null when undefined

The campaigns resource is intentionally read-only: it never sends or schedules a campaign. Trigger mass sends from the dashboard, not the SDK.

Paginated endpoints return a Paginated DTO exposing ->data (mapped DTOs), ->meta and ->links. The tags endpoint returns a flat Tag[] array.

Automatic pagination

Paginated resources also expose a cursor() generator that lazily walks every page for you, fetching one page at a time and yielding each mapped DTO. You never track page numbers — just iterate:

foreach ($client->contacts()->cursor(['status' => 'subscribed']) as $contact) {
    echo $contact->email.PHP_EOL;
}

// Available cursors (each yields the same DTOs as the matching list()):
$client->contacts()->cursor($query);           // Contact
$client->messages()->cursor($query);           // Message
$client->campaigns()->cursor($query);          // Campaign
$client->lists()->cursor($query);              // ContactList
$client->lists()->contactsCursor($id, $query); // Contact
$client->templates()->cursor($query);          // Template

A cursor() returns a plain \Generator (the core SDK never depends on Illuminate). In a Laravel app you can wrap it in a LazyCollection to use the collection pipeline:

use Illuminate\Support\LazyCollection;

LazyCollection::make($client->contacts()->cursor())
    ->filter(fn ($contact) => $contact->status === 'subscribed')
    ->each(fn ($contact) => /* ... */);

Resilience (automatic retries)

When you let the SDK build its own HTTP client (the default — you do not inject a Guzzle client), it installs an automatic retry middleware with exponential backoff.

What is retried: network/connection errors, 5xx responses, and 429 rate-limit responses.
Idempotency safety: only requests that are safe to repeat are retried — GET/HEAD/OPTIONS/PUT/DELETE, or any request that carries an Idempotency-Key header. A POST/PATCH without an Idempotency-Key (e.g. an email()/batch() send made without idempotencyKey:) is never retried, so the transport can never duplicate a send. Pass an idempotency key to make sends retry-safe.
Retry-After: on a 429, the Retry-After header is honored (numeric seconds or an HTTP-date); otherwise the delay is exponential (min(retry_max_delay, retry_base_delay * 2 ^ attempt), no jitter).

Tune it through the optional options argument (4th constructor parameter):

$client = new MailerClient(
    baseUrl: 'https://app.example.com/api/v1',
    token: 'your-project-api-key',
    httpClient: null,
    options: [
        'retries' => 2,            // max retry attempts
        'retry_base_delay' => 200, // ms, exponential backoff base
        'retry_max_delay' => 5000, // ms, backoff cap
        'retry_on_status' => range(500, 599), // statuses to retry (429 always retried)
        'timeout' => 30,           // Guzzle request timeout (seconds)
        'connect_timeout' => 10,   // Guzzle connect timeout (seconds)
    ],
);

When you inject your own Guzzle client it is used as-is — add the retry middleware yourself via Mailer\Sdk\Http\RetryMiddleware::make() if you want it.

Error handling

Every non-2xx response is mapped to a typed exception. All exceptions extend Mailer\Sdk\Exception\MailerException and expose:

getErrorCode(): ?string — the machine code field
getStatus(): ?int — the HTTP status
getBody(): ?array — the raw decoded response envelope
getMessage(): string — the human-facing message (standard \Exception)

Exception	HTTP status	Notes
`AuthenticationException`	401	Missing/invalid/expired token.
`NotFoundException`	404	e.g. `contact_not_found`, `template_not_found`, `message_not_found`.
`ValidationException`	422	Validation failures and domain rejections (`recipient_suppressed`, `quota_exceeded`, `template_not_found`, `invalid_status_transition`, ...). Adds `errors(): array` (field => messages).
`RateLimitException`	429	Adds `retryAfter(): ?int` parsed from the `Retry-After` header.
`MailerConfigurationException`	— (local)	Missing/empty/placeholder base URL or empty token; thrown at client construction before any request.
`UnsupportedFeatureException`	— (local)	The send relies on something the `/send` API has no field for (e.g. attachments).
`MailerException`	any other	Base class; also the catch-all for unexpected non-2xx statuses.

use Mailer\Sdk\Exception\ValidationException;
use Mailer\Sdk\Exception\RateLimitException;
use Mailer\Sdk\Exception\MailerException;

try {
    $client->send()->email(['to' => 'jane@example.com', 'template' => 'welcome']);
} catch (ValidationException $e) {
    if ($e->getErrorCode() === 'recipient_suppressed') {
        // address is on the suppression list — skip it
    }
    $fieldErrors = $e->errors(); // ['to' => ['The to field is required.'], ...]
} catch (RateLimitException $e) {
    sleep($e->retryAfter() ?? 1);
    // ...retry
} catch (MailerException $e) {
    report($e);
}

Laravel integration

The package is auto-discovered (no manual provider/alias registration). It registers a container-bound MailerClient singleton, a Mailer facade, a mailer mail transport and a mailer notification channel — all driven by the same mailer-sdk config.

Configuration

Publish the config file:

php artisan vendor:publish --tag=mailer-sdk-config

Then set the env vars (every key below maps to config/mailer-sdk.php):

# Connection (REQUIRED — no default; see the fail-loud note below)
MAILER_BASE_URL=https://app.example.com/api/v1
MAILER_API_TOKEN=your-project-api-key

# HTTP transport / resilience
MAILER_TIMEOUT=10
MAILER_RETRIES=2
MAILER_RETRY_BASE_DELAY=200
MAILER_RETRY_MAX_DELAY=5000

# Mail transport behavior
MAILER_MAIL_ATTACHMENTS=fail        # fail | ignore
MAILER_MAIL_IDEMPOTENCY=content     # content | random | off

Resolve the client from the container:

use Mailer\Sdk\MailerClient;

public function __construct(private MailerClient $mailer) {}

// ...
$this->mailer->send()->email([...]);

The resilience knobs (MAILER_TIMEOUT, MAILER_RETRIES, MAILER_RETRY_BASE_DELAY, MAILER_RETRY_MAX_DELAY) are wired into the container-bound client automatically.

Fail-loud connection config. MAILER_BASE_URL and MAILER_API_TOKEN have no working default. Constructing the client (resolving the MailerClient singleton, or sending the first message) with an unset/empty/placeholder base URL or an empty token throws a Mailer\Sdk\Exception\MailerConfigurationException with a clear message, instead of silently sending to a dead host. Set both before sending.

Mail transport (`MAIL_MAILER=mailer`)

The package registers a mailer mail driver, so you can route Laravel's Mail facade (and notifications, queued mailers, etc.) through the platform /send API without changing any mailing code.

Add a mailer entry to config/mail.php:

'mailers' => [
    // ...
    'mailer' => [
        'transport' => 'mailer',
    ],
],

and select it:

MAIL_MAILER=mailer

Now every send flows through the API:

// Plain message
Mail::raw('Hello world', fn ($m) => $m->to('jane@example.com')->subject('Hi'));

// A Mailable
Mail::to('jane@example.com')->send(new WelcomeMail($user));

The transport maps the message to a single /send call (one recipient) or a /send/batch call (multiple recipients), reading the subject, HTML body and text body off the message.

Sending with a stored template

To render a platform template by slug instead of inline HTML, set the template headers on the underlying Symfony message from your Mailable. The transport then sends a template payload ({to, template, variables}) and ignores the inline subject/body:

use Mailer\Sdk\Laravel\Mail\MailerHeaders;

class WelcomeMail extends Mailable
{
    public function build()
    {
        return $this
            ->subject('Welcome') // ignored when a template header is present
            ->withSymfonyMessage(function ($message) {
                $headers = $message->getHeaders();
                $headers->addTextHeader(MailerHeaders::TEMPLATE, 'welcome');
                $headers->addTextHeader(
                    MailerHeaders::VARIABLES,
                    json_encode(['first_name' => 'Jane']),
                );
            });
    }
}

Behavior & limitations

The platform /send API is intentionally narrow; the transport adapts to it with explicit, documented behavior rather than silent surprises.

From / Reply-To are ignored. The API does not accept from or reply_to — the platform always uses the project's configured sender (set the project default_from_email/default_from_name and a verified sending domain in the dashboard). A From set on the message is logged at debug level and dropped.
Attachments are not supported. The /send API has no attachment field. By default (mailer-sdk.mail.attachments = 'fail', env MAILER_MAIL_ATTACHMENTS) a message carrying an attachment throws Mailer\Sdk\Exception\UnsupportedFeatureException, so the send fails loudly and you fix the Mailable. Set it to 'ignore' to log a warning and send the message without the attachments. Attachments are never dropped silently in 'fail' mode.
Suppressed recipients are not failures. When the platform rejects an address as suppressed (recipient_suppressed), the transport does not throw: it logs a warning and dispatches a Mailer\Sdk\Laravel\Events\MessageSuppressed event (carrying the recipient email and reason). In a batch send, each suppressed recipient gets its own event while the rest are delivered. Listen for the event to prune your lists.
Quota / sending-domain rejections are failures. quota_exceeded and sending_domain_not_verified (and any other unexpected API error) are re-thrown as a Symfony\Component\Mailer\Exception\TransportException with the SDK exception kept as previous, so Laravel's mailer/queue treats the send as failed and can retry per your own policy. A batch send throws if any recipient hard-fails, summarizing the failed recipients.
Multiple recipients become a batch. To + Cc + Bcc are merged into the delivery list; each recipient is sent its own copy via /send/batch (the message content is shared, the to differs per item).
Idempotency is automatic and retry-safe. Per send the transport sets an Idempotency-Key derived from mailer-sdk.mail.idempotency (env MAILER_MAIL_IDEMPOTENCY):
- content (default): a deterministic hash of the message content, so a requeued job never duplicates the send. Two genuinely identical messages sent within the platform's idempotency window dedup — switch to random if that is not what you want.
- random: a fresh UUID per send attempt (no dedup).
- off: no key. Override per message with the X-Mailer-Idempotency-Key (MailerHeaders::IDEMPOTENCY_KEY) header.

Notification channel

The SDK also registers a mailer notification channel, so a Notification can deliver through the platform /send API by returning ['mailer'] from via() and defining toMailer($notifiable).

toMailer() returns a Mailer\Sdk\Laravel\Mail\MailerMessage for full control. Inline mode uses subject()/html()/text():

use Mailer\Sdk\Laravel\Mail\MailerMessage;

public function toMailer($notifiable): MailerMessage
{
    return (new MailerMessage)
        ->subject('Your order shipped')
        ->html('<p>It is on the way.</p>')
        ->text('It is on the way.');
}

Template mode renders a stored template with per-recipient variables:

return (new MailerMessage)
    ->template('order-shipped')
    ->variables(['name' => $notifiable->name]);

Recipient routing precedence: an explicit MailerMessage::to() wins, then routeNotificationFor('mailer'), then routeNotificationFor('mail'), then a public $email property on the notifiable.

Other return types are accepted too: a plain /send payload array is used directly (its to/idempotency_key keys are honored), and an Illuminate\Contracts\Mail\Mailable is rendered to its subject + HTML only — return a MailerMessage for templates, a text part or an explicit idempotency key.

The outcome semantics mirror the transport: a suppressed recipient is not a failure — a Mailer\Sdk\Laravel\Events\MessageSuppressed event is dispatched and the send is skipped — while quota / sending-domain / any other API error is rethrown so Laravel marks the notification failed and retries per your queue policy.

A complete notification:

use Illuminate\Notifications\Notification;
use Mailer\Sdk\Laravel\Mail\MailerMessage;

class OrderShipped extends Notification
{
    public function via($notifiable): array
    {
        return ['mailer'];
    }

    public function toMailer($notifiable): MailerMessage
    {
        return (new MailerMessage)
            ->subject('Your order shipped')
            ->html('<p>It is on the way.</p>');
        // Or a stored template:
        // return (new MailerMessage)->template('order-shipped')->variables(['name' => $notifiable->name]);
    }
}

Facade

The package registers a Mailer facade (auto-registered via package discovery) that proxies the same container-bound MailerClient singleton — no separate configuration is needed:

use Mailer\Sdk\Laravel\Facades\Mailer;

Mailer::contacts()->list();
Mailer::send()->email([
    'to' => 'jane@example.com',
    'subject' => 'Hello',
    'body' => '<p>Hi</p>',
]);

Contributing / Development

composer install
composer test        # alias for: vendor/bin/phpunit

Tests run entirely against a Guzzle MockHandler — no network access required.

For how this package is split out of the monorepo into its own repository, tagged with SemVer and published to Packagist, see PUBLISHING.md.

mosaiqo / mailer-php

Maintainers

Package info

Statistics

Security

README

Features

Requirements

Installation

Path repository (monorepo development)

Quick start: integrate into a Laravel app

Plain PHP usage

Batch sends

Idempotency

Other resources

Automatic pagination

Resilience (automatic retries)

Error handling

Laravel integration

Configuration

Mail transport (`MAIL_MAILER=mailer`)

Sending with a stored template

Behavior & limitations

Notification channel

Facade

Contributing / Development

mosaiqo / mailer-php

Maintainers

Package info

Statistics

Security

README

Features

Requirements

Installation

Path repository (monorepo development)

Quick start: integrate into a Laravel app

Plain PHP usage

Batch sends

Idempotency

Other resources

Automatic pagination

Resilience (automatic retries)

Error handling

Laravel integration

Configuration

Mail transport (MAIL_MAILER=mailer)

Sending with a stored template

Behavior & limitations

Notification channel

Facade

Contributing / Development

Mail transport (`MAIL_MAILER=mailer`)