PHP subscribe - simple subscribe functionality responding in json format

gistfile1.php

<?php
$email = (string) filter_input( INPUT_GET, 'email', FILTER_SANITIZE_EMAIL);
$email = filter_var( $email, FILTER_VALIDATE_EMAIL);

$name = (string) filter_input( INPUT_GET, 'name', FILTER_SANITIZE_SPECIAL_CHARS);

if( $email) {
    $pdo = new PDO('mysql:host=127.0.0.1;dbname=database', 'username', 'password');
    $stm = $pdo->prepare("SELECT COUNT(*) FROM `subscribes` WHERE `email` = ? ;");
    $stm->execute([$email]);

    if( ! $stm->fetchColumn() && $ip_address = getClientIp()){
        $stm = $pdo->prepare("INSERT INTO `subscribes` (`email`,`name`,`ip_address`) VALUES (?, ?, ?);");
        $stm->execute([$email, $name, $ip_address]);
        if( $stm->rowCount()) {
            $return = ['status'=>'success', 'msg'=>'You are now subscribed'];
        } else {
            $return = ['status'=>'error', 'msg'=>'We were unable to subscribe you'];
        }
    } else {
            $return = ['status'=>'error', 'msg'=>'You are already subscribed'];
    }
} else {
    $return = ['status'=>'error', 'msg'=>'Missing/Invalid e-mail address'];
}

function getClientIp( $proxy = FALSE) {
    if( $proxy) {
      if ( !empty($_SERVER['HTTP_CLIENT_IP']))
        return $_SERVER['HTTP_CLIENT_IP'];
      if ( !empty($_SERVER['HTTP_X_FORWARDED_FOR']))
        return $_SERVER['HTTP_X_FORWARDED_FOR'];
      return FALSE;
    }
    return !empty($_SERVER['REMOTE_ADDR']) ? $_SERVER['REMOTE_ADDR'] : FALSE;
}

header('Content-Type: application/json');
echo json_encode($return);