Change the email address for all admin related checkout emails in Paid Memberships Pro.

my_pmpro_change_admin_to_email_for_checkout.php

<?php
/**
 * Change the email address for all admin related checkout emails in Paid Memberships Pro.
 *
 * 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_change_admin_to_email_for_checkout( $user_email, $email ) {
	if ( strpos( $email->template, 'checkout_' ) !== false && strpos( $email->template, '_admin' ) !== false ) {
		$user_email = '[email protected]'; // Set recipient email here.
	}

	return $user_email;
}
add_filter( 'pmpro_email_recipient', 'my_pmpro_change_admin_to_email_for_checkout', 10, 2 );

Based on https://gist.github.com/andrewlimaza/78a4e1fb266b633aa5b138047576bfcc by @andrewlimaza