<?php
 
/**
* Implements MailSystemInterface
* Taken from http://www.ardoubleyou.com/blog/how-programmatically-send-e-mail-using-html-and-text-content-type-drupal-7
*/
class BookingMailSystem implements MailSystemInterface {
  /** 
   * Concatenate and wrap the e-mail body for plain-text mails
   * @param $message
   *  A message array, as described in hook_mail_alter().
   *
   *  @return
   *    The formatted $message
   */  
  public function format(array $message) {
    $message['body'] = implode("\n\n", $message['body']);
    return $message;
  }
 
  /** 
   * Send an e-mail message, using Drupal variables and default settings.
   * @see drupal_mail*()
   * @param $message
   *  A message array, as described in hook_mail_alter()
   *  @return
   *    TRUE if the mail was successfully accepted, otherwise FALSE
   */  
  public function mail(array $message) {
    $mimeheaders = array();
    foreach($message['headers'] as $name => $value) {
      $mimeheaders[] = $name . ': ' . mime_header_encode($value);
    }   
    $line_endings = variable_get('mail_line_endings', MAIL_LINE_ENDINGS);
    return mail(
      $message['to'],
      mime_header_encode($message['subject']),
      preg_replace('@\r?\n@', $line_endings, $message['body']),
      join("\n", $mimeheaders)
    );
  }
}