marko/mail-log

Log-based mail driver --- writes emails to the log instead of sending them, for development and testing. Implements MailerInterface from marko/mail by writing email details to the logger rather than delivering them. Envelope metadata (from, to, subject, attachment names) is logged at info level; in development, full HTML/text bodies are also logged at debug level. Every send() call returns true since no delivery can fail.

The driver refuses to boot in production: a log driver delivers no mail, and message bodies carry password-reset links and verification tokens that anyone with log access could use.

Installation

Install it as a development dependency so it is never deployed:

composer require --dev marko/mail-log

This automatically installs marko/mail and marko/log.

Usage

Automatic via Binding

Installing the package binds MailerInterface to LogMailer --- no configuration is needed. Its module.php does the binding for you:

module.php

use Marko\Mail\Contracts\MailerInterface;
use Marko\Mail\Log\LogMailer;

return [
    'bindings' => [
        MailerInterface::class => LogMailer::class,
    ],
];

Use a real driver such as marko/mail-smtp in production. Because marko/mail-log is a require-dev dependency, composer install --no-dev leaves it out of production builds and the production driver’s binding is the only one.

Production Guard

If marko/mail-log is installed while the application runs in production (MARKO_ENV/APP_ENV set to production or prod, or unset), the application refuses to boot with a MailLogException explaining the risk. The guard checks whether the package is installed, not which mailer a binding resolves to: an app module that overrides MailerInterface for production still trips it, so keep the package out of production builds rather than overriding its binding.

To log mail in production deliberately, opt in:

config/mail-log.php

return [
    'allow_production' => true,
];

or set MAIL_LOG_ALLOW_PRODUCTION=true. Bodies stay excluded in production unless you also set include_body to true.

What Gets Logged

When you send a message in development, the log output includes:

[2025-01-15 10:30:00] app.INFO: Email sent {"from":"[email protected]","to":["[email protected]"],"subject":"Welcome!","has_html":true,"has_text":false,"attachment_count":0}
[2025-01-15 10:30:00] app.DEBUG: Email body (html) {"body":"<h1>Welcome!</h1>"}

The info-level entry captures envelope metadata --- from address, recipients, subject, whether HTML/text bodies are present, and attachment count. If the message includes CC, BCC, or attachments, those details are included as well (attachment name, size, and MIME type). When bodies are included, the debug-level entries log the full message body for each content type (text and/or HTML).

For sendRaw(), the info entry logs the recipient and raw content length; when bodies are included, a debug entry logs the full raw content.

Outside development, only the info entries are written.

Your code stays the same regardless of driver:

use Marko\Mail\Contracts\MailerInterface;
use Marko\Mail\Message;

class WelcomeMailer
{
    public function __construct(
        private MailerInterface $mailer,
    ) {}

    public function sendWelcome(
        string $email,
    ): void {
        $message = Message::create()
            ->to($email)
            ->from('[email protected]')
            ->subject('Welcome!')
            ->html('<h1>Welcome!</h1>');

        $this->mailer->send($message);
    }
}

Configuration

config/mail-log.php

use Marko\Config\Env;

return [
    'include_body' => null,
    'allow_production' => Env::bool('MAIL_LOG_ALLOW_PRODUCTION', false),
];

Key	Default	Description
include_body	null	Log text/HTML bodies and raw content at debug level. null logs them only in development (development, dev, local); true or false forces the choice in every environment.
allow_production	false	Let the application boot with this driver installed in production.

API Reference

LogMailer

Implements MailerInterface. See marko/mail for the full interface contract.

Method	Description
send(Message $message): bool	Log envelope metadata at info level and, when bodies are included, each body at debug level; always returns true
sendRaw(string $to, string $raw): bool	Log recipient and raw content length at info level and, when bodies are included, the full content at debug level; always returns true

The constructor takes the logger and the package config:

use Marko\Log\Contracts\LoggerInterface;
use Marko\Mail\Log\Config\MailLogConfig;

public function __construct(
    private LoggerInterface $logger,
    private MailLogConfig $config,
) {}

MailLogConfig

Method	Description
includeBody(): bool	The resolved mail-log.include_body, falling back to “development only” when it is null
allowProduction(): bool	mail-log.allow_production

ProductionGuard

Runs from the module’s boot callback. check(): void throws MailLogException when the environment is production and allow_production is false.