Copy an additional email address when admin approval is required for a specific membership level.

pmpro-customizations.php

<?php

/**
 * This recipe copies an additional email address when admin approval is
 * required for a specific membership level.
 *
 * It is intended for use with the Approval Process for Membership Add On:
 * https://www.paidmembershipspro.com/add-ons/approval-process-membership/
 *
 * You can add this recipe to your site by creating a custom plugin
 * or using the Code Snippets plugin available for free in the WordPress repository.
 * Read this companion article for step-by-step directions on either method.
 * https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */
function my_pmpro_email_filter($email) {
	$membership_level_id = 1; // use target membership level
	$email_to_copy = "test@example.com"; // use correct email address

	if (
		$email->template === 'admin_notification_approval' &&
		$email->data['membership_id'] === $membership_level_id
	) {
		// Make sure we have a headers array
		if ( empty( $email->headers ) ) {
			$email->headers = array();
		} elseif ( ! is_array( $email->headers ) ) {
			$email->headers = array( $email->headers );
		}

		$email->headers[] = "Cc:" . $email_to_copy;
	}

	return $email;
}

add_filter( 'pmpro_email_filter', 'my_pmpro_email_filter' , 10, 1);