functions.php

<?php
// Predefined email address
define('HIDDEN_EMAIL_ORDERS', 'email@tohide.com');

// Add the checkbox
function add_email_filter_checkbox() {
    global $typenow;
    
    if ( 'shop_order' == $typenow ) {
        $is_checked = isset( $_GET['hide_specific_email'] ) ? 'checked' : '';
        echo '<label style="margin-right:10px;margin-left:10px;"><input style="height:1rem;" type="checkbox" name="hide_specific_email" value="1" ' . $is_checked . '> Hide orders from ' . HIDDEN_EMAIL_ORDERS . '</label>';
    }
}
add_action( 'restrict_manage_posts', 'add_email_filter_checkbox' );

// Filter orders based on the checkbox value
function filter_orders_by_checkbox( $query ) {
    global $typenow, $wpdb;
    
    if ( 'shop_order' == $typenow && isset( $_GET['hide_specific_email'] ) && '1' == $_GET['hide_specific_email'] ) {
        $order_ids = $wpdb->get_col( $wpdb->prepare(
            "SELECT pm.post_id FROM {$wpdb->postmeta} pm WHERE pm.meta_key = '_billing_email' AND pm.meta_value = %s",
            HIDDEN_EMAIL_ORDERS
        ) );

        // Adjust the main query to exclude orders with the specified email
        $query->set( 'post__not_in', $order_ids );
    }
}
add_action( 'pre_get_posts', 'filter_orders_by_checkbox' );