email_queue.sql

CREATE TABLE IF NOT EXISTS `email_queue` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `created_at` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `recipients` text NOT NULL,
  `final_body` text,
  `headers` text,
  `send_after` datetime DEFAULT NULL,
  `subject` varchar(255) DEFAULT NULL,
  `priority` tinyint(4) NOT NULL DEFAULT '3',
  `ip_address` varchar(16) DEFAULT NULL,
  `spam_status` tinyint(4) NOT NULL DEFAULT '0',
  `sent_at` timestamp NULL DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=utf8 AUTO_INCREMENT=19 ;

example.php

<?php
//sending e-mail (adding to queue)
$this->load->library('email');
$this->email->initialize();
$this->email->from('john@doe');
$this->email->set_protocol("queue");
$this->email->send_at("+1 day");//strtotime format
$this->email->to('foo@bar');
$this->email->subject('subject');
$this->email->message('msg');
$queue_id = $this->email->send();


//fetching queue
$this->load->library('email');
$this->email->initialize();
if($this->email->setup_email_from_queue()) // or $this->email->setup_email_from_queue($queue_id);
    var_dump($this->email->send()); //bool

MY_Email.php

<?php

/**
 * CodeIgniter
 *
 * An open source application development framework for PHP 5.2.4 or newer
 *
 * NOTICE OF LICENSE
 *
 * Licensed under the Open Software License version 3.0
 *
 * This source file is subject to the Open Software License (OSL 3.0) that is
 * bundled with this package in the files license.txt / license.rst.  It is
 * also available through the world wide web at this URL:
 * http://opensource.org/licenses/OSL-3.0
 * If you did not receive a copy of the license and are unable to obtain it
 * through the world wide web, please send an email to
 * licensing@ellislab.com so we can send you a copy immediately.
 *
 * @package		CodeIgniter
 * @author		EllisLab Dev Team
 * @copyright	Copyright (c) 2008 - 2013, EllisLab, Inc. (http://ellislab.com/)
 * @license		http://opensource.org/licenses/OSL-3.0 Open Software License (OSL 3.0)
 * @link		http://codeigniter.com
 * @since		Version 1.0
 * @filesource
 */
defined('BASEPATH') OR exit('No direct script access allowed');

class MY_Email extends CI_Email {

    /**
     * Valid $protocol values
     *
     * @see	CI_Email::$protocol
     * @var	string[]
     */
    protected $_send_after = null;
    protected $_protocols = array('mail', 'sendmail', 'smtp', 'queue');
    protected $_queue_table = 'email_queue';
    protected $_queue_id = null;

    /**
     * Set Email Queue Table name
     *
     * @param	string
     * @return	MY_Email
     */
    public function set_queue_table($table) {
        $CI =& get_instance();
        if ($CI->db->table_exists($table)) {
            $this->_table = $table;
        }
        $this->_set_error_message('lang:email_queue_table_not_exists', $table);
        return $this;
    }

    /**
     * Set Email Subject
     *
     * @param	string
     * @return	MY_Email
     */
    public function subject($subject) {
        $subject = $this->_prep_q_encoding($subject);
        $this->set_header('Subject', $subject);
        $this->_subject = $subject;
        return $this;
    }

    /**
     * Schedule Email sending
     *
     * @param	string/datetime
     * @return	MY_Email
     */
    public function send_after($datetime) {
        $time = strtotime($datetime);
        if (!$time || $time === -1) {
            $this->_set_error_message('lang:email_invalid_strtotime_string_for_send_after', $datetime);
            return false;
        }
        $this->_send_after = strftime("%Y-%m-%d %H:%M:%S", $time);
        return $this;
    }

    /**
     * Send using queue table() protocol
     *
     * @return	insert_id;
     */
    protected function _send_with_queue() {
        $this->_recipients = serialize($this->_recipients);
        $CI =& get_instance();
        if ($CI->db->insert($this->_queue_table, array('recipients' => $this->_recipients, 'subject' => $this->_subject,
                'final_body' => $this->_finalbody, 'headers' => serialize($this->_headers),
                'priority' => $this->priority, 'ip_address' => $CI->input->ip_address(),
                'send_after' => $this->_send_after, 'body_hash' => hash("sha256", $this->_finalbody))))
            return $CI->db->insert_id();
    }

    /**
     * Fetches next queue email from email queue table based upon priority, send_after
     * TODO: check send_after, spam possibility, etc
     *
     * @return	E-mail data;
     */
    protected function _fetch_next_email_from_queue() {
        $CI =& get_instance();
        $CI->db->where('sent_at', null);
        $CI->db->order_by('created_at', 'ASC');
        $CI->db->limit(1);
        $email = $CI->db->get($this->_queue_table);
        if ($email->num_rows())
            return $email->row();
    }
    /**
     * Fetches queued email based on its ID, else fetches next email
     *
     * @return	E-mail data;
     */
    protected function _fetch_email_from_queue($queue_id) {
        $CI =& get_instance();
        $queue_id = (int) $queue_id;
        if ($queue_id) {
            $CI->db->where("id", $queue_id);
            $email = $CI->db->get($this->_queue_table);
            if ($email->num_rows())
                return $email->row();
        } else {
            return $this->_fetch_next_email_from_queue();
        }
    }

    /**
     * Sets up e-mail using queue table()
     *
     * @return	MY_Email;
     */
    public function setup_email_from_queue($queue_id = false) {
        $this->clear();
        $email_data = $this->_fetch_email_from_queue($queue_id);
        if ($email_data) {
            $this->_queue_id = $email_data->id;
            $this->_headers = unserialize($email_data->headers);
            $this->_final_body = $email_data->final_body;
            $this->_recipients = unserialize($email_data->recipients);
            $this->_subject = $email_data->subject;
            return true;
        }
    }

    public function clear($clear_attachments = false) {
        $this->_send_after = null;
        $this->_queue_id = null;
        parent::clear();
    }

    /**
     * Spool mail to the mail server
     *
     * @return	bool
     */
    protected function _spool_email() {
        $this->_unwrap_specials();

        $method = '_send_with_' . $this->_get_protocol();
        if (!$result = $this->$method()) {
            $this->_set_error_message('lang:email_send_failure_' . ($this->_get_protocol() === 'mail' ? 'phpmail' : $this->_get_protocol()));
            return FALSE;
        }
        //update sent_at now() on queue table
        if ($this->_queue_id) {
            $CI =& get_instance();
            $CI->db->where("id", $this->_queue_id);
            $CI->db->update($this->_queue_table, array('sent_at' => strftime("%Y-%m-%d %H:%M:%S", time())));
        }
        $this->_set_error_message('lang:email_sent', $this->_get_protocol());
        return $result;
    }

}

/* End of file MY_Email.php */
/* Location: ./application/libraries/MY_Email.php */