moritabox-smtp

Overview

SMTP server built with ReactPHP, supports PLAIN, LOGIN and CRAM-MD5 authentication.

An easy way to run a local SMTP server for testing mail implementations.

Requirements

• php: >=8.1
• react/socket: ^1.13

Installation

The easiest way to install it is to use Composer:

  composer require vecode/moritabox-smtp

Basic usage

Create an SmtpServer instance by passing an authentication callback; then subscribe to the ready, mail and/or error events:

use MoritaBox\Smtp\Mail;
use MoritaBox\Smtp\SmtpServer;
use MoritaBox\Smtp\SmtpHandler;

$server = new SmtpServer(function(string $user, SmtpHandler $handler) {
    return $user == '[email protected]' ? 'secret' : false;
});

$server->on('ready', function(int $port) use ($output) {
    echo "Listening on port {$port}";
});

$server->on('mail', function(Mail $mail, SmtpHandler $handler) use ($output) {
    $filename = 'mail-'.microtime(true).'.eml';
    echo "Mail received, saving as '{$filename}'";
    file_put_contents(dirname(__FILE__) . DIRECTORY_SEPARATOR . $filename, $mail->getContents());
});

$server->on('error', function(Exception $e) use ($output) {
    $message = sprintf('%s @ %s:%d', $e->getMessage(), $e->getFile(), $e->getLine());
    echo $message;
});

$server->start();

The ready event is fired when the server is initialized and listening, the error event signals ReactPHP's Socket errors.

Finally, the mail event is fired when a complete mail message has been received, with a Mail instance which contains the from address, recipient addresses and all its contents in plain-text form so that you can store it or parse with a MIME message parser (for example by using the mailparse extension).

Note that you can change the listening port (defaults to 8025) from the SmtpServer constructor and also you can specify the fully-qualified domain for the CRAM-MD5 challenge and also set a flag so that the port is bound only locally (that is, allow connections from 127.0.0.1 only).

SSL/TLS is supported only in implicit mode, that is, the connection starts out with a secure handshake. For it to work you will need to enable it and pass the certificate and private key location (if required):

$server->start(true, [
    'local_cert' => '/home/contosso/certs/contosso-certificate.pem',
    'local_pk' => '/home/contosso/certs/contosso-key.pem',
]);

As you can see, the second parameter is an SSL context options listing as defined here.

STARTTLS is not supported due to a ReactPHP limitation.

Authentication

Each of the supported authentication methods require you to provide an authentication callback that will receive the user name and must return the password for that user or false for non-existing users. As you can see, the returned password must be in plain-text, a limitation on the SMTP protocol, so it is advised to encrypt the passwords if you store them (in a database for example).

If you do not provide an authentication callback, it will be disabled, but it is generally not recommended unless you know what you are doing. For example, relay servers don't require authentication but they must validate the recipient address and reject the message if it is not valid.

Validation

You can also validate the sender/recipient (depending on the server's purpose) by means of the setMailCallback and setRecipientCallback methods, both of them take a Closure as argument that in turn receives an $email parameter; just return true to allow the address or false to deny it.

$server->setRecipientCallback(function(string $email, SmtpHandler $handler) {
    # Check for specific domain
    return str_ends_with($email, '@example.org');
});

This example uses a pretty simple approach, but you may use a regular expression or any other advanced mechanism to validate it should you like to.

Using PHPMailer to send mail

The most-common use case is testing email sent from other PHP projects, commonly implemented with PHPMailer or similar libraries.

In the following example you can see a basic setup; the most important bit is the authentication parameters (SMTPAuth, Username and Password, the later two will be checked via the authentication callback described in the previous section):

use PHPMailer\PHPMailer\PHPMailer;

$mail = new PHPMailer();

$mail->isSMTP();
$mail->Host = 'localhost';
$mail->Port = 8025;
$mail->SMTPAuth = true;
$mail->Username = '[email protected]';
$mail->Password = 'secret';
$mail->SMTPDebug = true;
$mail->Timeout = 15;

$mail->setFrom('[email protected]', 'Mailer');
$mail->addAddress('[email protected]', 'Joe User');
$mail->addAddress('[email protected]');
$mail->addReplyTo('[email protected]', 'Information');
$mail->addCC('[email protected]');
$mail->addBCC('[email protected]');

$mail->Subject = 'Here is the subject';
$mail->Body    = 'This is the HTML message body <b>in bold!</b>';
$mail->AltBody = 'This is the body in plain text for non-HTML mail clients';

if(!$mail->send()) {
    echo 'Message could not be sent.';
    echo 'Mailer Error: ' . $mail->ErrorInfo;
} else {
    echo 'Message has been sent';
}

If you have enabled implicit SSL you must also set the SMTPSecure option as follows:

$mail->SMTPSecure = PHPMailer::ENCRYPTION_SMTPS;

License

MIT licensed

Copyright © 2023 Vecode. All rights reserved.