Send email with PHP /MySQL usning Sendgrid

I use SendGrid SMTP to send out emails from PHP/MySQL application. Sendgrid has its own PHP Library and has a feature called "Substitution" which works like mail merge. I need some one to fix this code below so I can use it in my application. This is the code below: $sendgrid = new SendGrid(SENDGRID_USER,SENDGRID_PASS); $mail = new SendGrid\Mail(); $mail->setFrom(EMAIL_FROM)->setFromName(EMAIL_NAME)->setSubject('Order %order_id%')->setText($text)->setHtml($html); $mail->addCategory('Order'); $Substitutions = array('order_id'=>array(),'username'=>array(),'name'=>array(),'email'=>array()); foreach ($emails as $email){ $Substitutions['order_id'][] = $email['order_id']; $Substitutions['username'][] = $email['username']; $Substitutions['name'][] = $email['name']; $Substitutions['email'][] = $email['email']; $mail->addTo($email['email'],$email['name']); } $mail->addSubstitution("%order_id%", $Substitutions['order_id']); $mail->addSubstitution("%username%", $Substitutions['username']); $mail->addSubstitution("%name%", $Substitutions['name']); $mail->addSubstitution("%email%", $Substitutions['email']); $sendgrid->smtp->send($mail); unset($mail);