Making PHP's mail() asynchronous

Question

I have PHP's mail() using ssmtp which doesn't have a queue/spool, and is synchronous with AWS SES.

I heard I could use SwiftMail to provide a spool, but I couldn't work out a simple recipe to use it like I do currently with mail().

I want the least amount of code to provide asynchronous mail. I don't care if the email fails to send, but it would be nice to have a log.

Any simple tips or tricks? Short of running a full blown mail server? I was thinking a sendmail wrapper might be the answer but I couldn't work out nohup.

Answer 1

You have a lot of ways to do this, but handling thread is not necessarily the right choice.

• register_shutdown_function: the shutdown function is called after the response is sent. It's not really asynchronous, but at least it won't slow down your request. Regarding the implementation, see the example.
• Swift pool: using symfony, you can easily use the spool.
• Queue: register the mails to be sent in a queue system (could be done with RabbitMQ, MySQL, redis or anything), then run a cron that consume the queue. Could be done with something as simple as a MySQL table with fields like from, to, message, sent (boolean set to true when you have sent the email).

Example with register_shutdown_function

<?php
class MailSpool
{
  public static $mails = [];

  public static function addMail($subject, $to, $message)
  {
    self::$mails[] = [ 'subject' => $subject, 'to' => $to, 'message' => $message ];
  }

  public static function send() 
  {
    foreach(self::$mails as $mail) {
      mail($mail['to'], $mail['subject'], $mail['message']);
    }
  }
}

//In your script you can call anywhere
MailSpool::addMail('Hello', '[email protected]', 'Hello from the spool');


register_shutdown_function('MailSpool::send');

exit(); // You need to call this to send the response immediately