Fix WooCommerce Email conflict with ET+

functions.php

<?php

add_action( 'wp_loaded', 'rt_remove_ticket_email', 80 );

/**
 * Remove the main filter of ET email and add it again with a check to prevent fatal errors
 */
function rt_remove_ticket_email() {

	if ( ! function_exists( 'tribe' ) ) {
		return;
	}

	remove_filter( 'woocommerce_email_classes', array( tribe( 'tickets-plus.commerce.woo' ), 'add_email_class_to_woocommerce' ) );

	add_filter( 'woocommerce_email_classes', function ( $classes ) {
		if ( ! class_exists( 'Tribe__Tickets_Plus__Commerce__WooCommerce__Email' ) ) {
			return $classes;
		}

		$classes['Tribe__Tickets__Woo__Email'] = new Tribe__Tickets_Plus__Commerce__WooCommerce__Email();

		return $classes;
	} );
}

This is deprecated since Event Tickets v4.10.8