Approve New Users Before They Can Log In

// Roles that need approval when they sign up (e.g. leave out "customer" so shop buyers are not blocked).
$wpide_approval_roles = array( 'subscriber' );

add_action( 'user_register', function ( $user_id ) use ( $wpide_approval_roles ) {
    if ( current_user_can( 'create_users' ) ) {
        return; // Created by an administrator (admin screen, REST API or WP-CLI).
    }

    $user = get_userdata( $user_id );

    if ( $user && array_intersect( (array) $user->roles, $wpide_approval_roles ) ) {
        update_user_meta( $user_id, 'wpide_pending_approval', 1 );
    }
} );

add_filter( 'authenticate', function ( $user ) {
    if ( $user instanceof WP_User && get_user_meta( $user->ID, 'wpide_pending_approval', true ) ) {
        return new WP_Error( 'wpide_pending_approval', '<strong>Your account is waiting for approval.</strong> You will get an email as soon as it is approved.' );
    }

    return $user;
}, 50 );

add_filter( 'login_message', function ( $message ) {
    if ( isset( $_GET['checkemail'] ) && 'registered' === $_GET['checkemail'] ) {
        $message .= '<p class="message">An administrator needs to approve your account before you can log in.</p>';
    }

    return $message;
} );

add_filter( 'manage_users_columns', function ( $columns ) {
    $columns['wpide_approval'] = 'Approval';

    return $columns;
} );

add_filter( 'manage_users_custom_column', function ( $output, $column, $user_id ) {
    if ( 'wpide_approval' !== $column ) {
        return $output;
    }

    if ( ! get_user_meta( $user_id, 'wpide_pending_approval', true ) ) {
        return 'Approved';
    }

    $url = wp_nonce_url( admin_url( 'admin-post.php?action=wpide_approve_user&user_id=' . (int) $user_id ), 'wpide_approve_user_' . (int) $user_id );

    return '<strong style="color:#b32d2e">Pending</strong><br><a href="' . esc_url( $url ) . '">Approve</a>';
}, 10, 3 );

add_action( 'admin_post_wpide_approve_user', function () {
    $user_id = isset( $_GET['user_id'] ) ? absint( $_GET['user_id'] ) : 0;

    if ( ! $user_id || ! current_user_can( 'edit_user', $user_id ) ) {
        wp_die( 'You are not allowed to approve this user.' );
    }

    check_admin_referer( 'wpide_approve_user_' . $user_id );
    delete_user_meta( $user_id, 'wpide_pending_approval' );

    $user = get_userdata( $user_id );
    if ( $user ) {
        wp_mail(
            $user->user_email,
            sprintf( '[%s] Your account has been approved', wp_specialchars_decode( get_bloginfo( 'name' ), ENT_QUOTES ) ),
            sprintf( "Hello %s,\n\nYour account is approved. You can log in here:\n%s", $user->display_name, wp_login_url() )
        );
    }

    wp_safe_redirect( admin_url( 'users.php' ) );
    exit;
} );