public static function send($from_email, $to_emails, $title_email, $title, $content, $attach_file = '')
 {
     //Create a new PHPMailer instance
     self::$mailer = new PHPMailer();
     self::$mailer->CharSet = 'UTF-8';
     //Tell PHPMailer to use SMTP
     self::$mailer->isSMTP();
     //Enable SMTP debugging
     // 0 = off (for production use)
     // 1 = client messages
     // 2 = client and server messages
     self::$mailer->SMTPDebug = 0;
     //Ask for HTML-friendly debug output
     self::$mailer->Debugoutput = 'html';
     //Set the hostname of the mail server
     self::$mailer->Host = 'smtp.gmail.com';
     //Set the SMTP port number - 587 for authenticated TLS, a.k.a. RFC4409 SMTP submission
     self::$mailer->Port = 587;
     //Set the encryption system to use - ssl (deprecated) or tls
     self::$mailer->SMTPSecure = 'tls';
     //Whether to use SMTP authentication
     self::$mailer->SMTPAuth = true;
     //Username to use for SMTP authentication - use full email address for gmail
     self::$mailer->Username = "******";
     //Password to use for SMTP authentication
     self::$mailer->Password = "******";
     //Set who the message is to be sent from
     self::$mailer->setFrom('noreply' . $from_email, $title_email);
     //Set an alternative reply-to address
     self::$mailer->addReplyTo('noreply' . $from_email, $title_email);
     //Set who the message is to be sent to
     if (is_array($to_emails)) {
         foreach ($to_emails as $email) {
             self::$mailer->addAddress($email['email'], $email['name']);
         }
     } else {
         self::$mailer->addAddress($to_emails, 'Thư góp ý');
     }
     //Set the subject line
     self::$mailer->Subject = $title;
     //Read an HTML message body from an external file, convert referenced images to embedded,
     //convert HTML into a basic plain-text alternative body
     self::$mailer->msgHTML($content, dirname(__FILE__));
     //Replace the plain text body with one created manually
     self::$mailer->AltBody = strip_tags($content);
     //Attach an image file
     self::$mailer->addAttachment($attach_file);
     //send the message, check for errors
     if (!self::$mailer->send()) {
         self::$error_mes = self::$mailer->ErrorInfo;
         return false;
     }
     return true;
 }