thefox/smtpd

SMTP server (library) written in pure PHP.

SMTPd

SMTP server (library) for receiving emails, written in pure PHP. This library provides an interface to the SMTP server-side protocol with PHP. It creates a \Zend\Mail\Message Class object for every incoming email and hands this object to a custom PHP function for further processing. The project is in Beta status, so it's not recommended for production use., _(*1)

The d in SMTPd stands for Daemon. This script can run in background like any other daemon process. It's not meant for running as a webapplication., _(*2)

Why this project?

Believe it or not, email is still the killer feature of the Internet. There are tons of projects like PHPMailer: to send emails programmatically (with PHP). But there are not so many to receive emails from SMTP., _(*3)

With this interface you can do something like this for your app users:, _(*4)

+------+     +------------------------+     +-------+     +--------------+
| User +---> | MUA (like Thunderbird) +---> | SMTPd +---> | Your PHP App |
+------+     +------------------------+     +-------+     +--------------+

This is useful when you have a messaging application written in PHP but no graphical user interface for it. So your graphical user interface can be any email client. Thunderbird for instance., _(*5)

Project Outlines

The project outlines as described in my blog post about Open Source Software Collaboration., _(*6)

• The main purpose of this software is to provide a server-side SMTP API for PHP scripts.
• Although the RFC implementations are not completed yet, they must be strict.
• More features can be possible in the future. In perspective of the protocols the features must be a RFC implementation.
• This list is open. Feel free to request features.

Planned Features

• Full RFC 821 implementation.
• Full RFC 1651 implementation.
• Full RFC 1869 implementation.
• Replace Zend\Mail with a better solution.

Installation

The preferred method of installation is via Packagist and Composer. Run the following command to install the package and add it as a requirement to composer.json:, _(*7)

composer require thefox/smtpd

Delivery

At the moment the server accepts all incoming emails. You decide what happens with incoming emails by adding Events to the Server object ($server->eventAdd($event)). The server can handle certain events. Each event will be executed on a certain trigger. Even if you don't add any Events to the Server it accepts all incoming emails., _(*8)

Events

At the moment there are two Event Triggers., _(*9)

• TRIGGER_NEW_MAIL: will be triggered when a Client has finished transmitting a new email.
• TRIGGER_AUTH_ATTEMPT: will be triggered when a Client wants to authenticate. Return a boolean from the callback function whether the authentication was successful or not.

Examples

See also example.php file for full examples., _(*10)

Trigger New Mail Example

$server = new Server(...);

$event = new Event(Event::TRIGGER_NEW_MAIL, null, function(Event $event, $from, $rcpts, $mail){
    // Do stuff: handle email, ...
});
$server->addEvent($event);
$server->loop();

Trigger Auth Example

$server = new Server(...);

$event = new Event(Event::TRIGGER_AUTH_ATTEMPT, null, function(Event $event, $type, $credentials): bool{
    // Do stuff: Check credentials against database, ...
    return true;
});
$server->addEvent($event);
$server->loop();

Use SMTP Server with own loop

$server = new Server(...);

// Set up server here.
// Add Events, etc, ...

while(myApplicationRuns()){
    // Do stuff your application needs.
    // ...

    // Run main SMTPd loop, once.
    $server->run();
    usleep(10000); // Never run a main thread loop without sleep. Never!
}

RFC 821 Implementation

Complete implementation

• 3.5 OPENING AND CLOSING

Incomplete implementation

• 3.1 MAIL
• 4.1.1 COMMAND SEMANTICS
  • HELO
  • MAIL
  • RCPT
  • DATA
  • NOOP
  • QUIT

RFC 1651 Implementation

Complete implementation

• 4.1.1 First command
• 4.5 Error responses from extended servers

RFC 3207 Implementation

RFC 4954 Implementation

• 1. The AUTH Command

Related Links

• RFC 821
• RFC 1425
• RFC 1651
• RFC 1869
• RFC 2821
• RFC 3207
• RFC 4954

Related Projects

• IMAPd

Project Links

• Packagist Package