BCC multiple email addresses, including the site admin email address, on all Event Tickets' RSVP ticket emails so they get a copy of it too

functions.php

<?php
/**
  * BCC multiple email addresses, including the site admin email address, on all Event Tickets' RSVP ticket emails so they get a copy of it too
  *
  * From https://gist.github.com/cliffordp/c4fb2ea8fb5ca44973ff06e6facc9742
  * A fork of https://gist.github.com/cliffordp/4f06f95dbff364242cf54a3b5271b182
  * For https://theeventscalendar.com/support/forums/topic/event-tickets-free-not-plus-rsvp-notifications/#post-1272819
  *
  * @link https://developer.wordpress.org/reference/functions/wp_mail/#comment-349
  */
function cliff_et_rsvp_bcc_admin_and_more_ticket() {
	$bccs = array(
	  get_option( 'admin_email' ), // the site admin email, probably do not want to edit this line
	  'someone@example.com', // edit or delete this line
	  'another@anywhere.com', // edit or delete this line, and even add another if you want
	);
	
	// set Headers to Event Tickets' default
	$headers = array( 'Content-type: text/html' );
	
	// add each BCC email if it's a valid email address
	foreach ( $bccs as $bcc ) {
		$bcc = sanitize_email( $bcc );
		
		if ( is_email( $bcc ) ) {
			$headers[] = sprintf( 'Bcc: %s', $bcc );
		}
	}
	
	return $headers;
}
add_filter( 'tribe_rsvp_email_headers', 'cliff_et_rsvp_bcc_admin_and_more_ticket' );