Since wc_mail doesn't seem to work perfectly, a custom version

wc_mail.php

<?php
/**
 * Our custom alternative to wc_mail.
 *
 * @param mixed  $to          Receiver.
 * @param mixed  $subject     Subject.
 * @param mixed  $message     Message.
 * @param string $headers     Headers. (default: "Content-Type: text/html\r\n").
 * @param string $attachments Attachments. (default: "").
 * @return bool
 */
function prefix_mail( $to, $subject, $message, $headers = "Content-Type: text/html\r\n", $attachments = "" ) {
	if( ! class_exists( 'WC_Emails' ) ) { include_once WC_ABSPATH . 'includes/class-wc-emails.php'; }
	$mailer  = WC()->mailer();
	$message = $mailer->wrap_message( $subject, $message );
	return $mailer->send( $to, $subject, $message, $headers, $attachments );
}