Функция отправка почты HTML 

function SendMail($from='', $to, $subject='', $message){         
         $headers  = "From: $from\n";
         $headers .= "Subject: $subject\n";
         $headers .= "Reply-To: $from\n";
         $headers .= "Mime-Version: 1.0\n";
         $headers .= 'Content-type: text/html; charset=UTF-8' . "\r\n";
         
         if(mail($to, $subject, $message, $headers)){
                  return true;
         }
}