pmpro-email-data-site-email.php

<?php
/**
 * Set the site email address for PMPro emails.
 *
 * 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_data_siteemail( $data, $email ) {
	// Set the site email address here:
	$data['siteemail'] = 'someone@example.com';

	return $data;
}
add_filter( 'pmpro_email_data', 'my_pmpro_email_data_siteemail', 50, 2 );