CC organizers on registrations

copy-all-organizers.php

<?php
/**
  * BCC event organizers email on all Event Tickets' RSVP and commerce ticket emails so they get a copy of it too
  */
function bcc_all_event_organizers( $headers, $event_id, $order_id ) {

    //check if has organizer
    if ( ! tribe_has_organizer( $event_id ) ) {
    	return $headers;
    }
    //get all organizers asociated to the event
    $event_organizers_ids = tribe_get_organizer_ids( $event_id );
    //get all the event organizers emails for the event
    $event_organizers_emails = array();
    foreach ( $event_organizers_ids as $organizer_id ) {
    	$organizer_email = tribe_get_organizer_email( $organizer_id, false );
    	//make sure it's a valid email
    	if ( is_email( $organizer_email ) ) {
		$event_organizers_emails[] = $organizer_email;
    	}
    }
    if ( empty( $event_organizers_emails ) ) {
    	return $headers;
    }

    $to = implode( ", ", $event_organizers_emails );

	$headers[] = sprintf( 'Bcc: %s', $to );

    return $headers;
}
add_filter( 'tribe_rsvp_email_headers', 'bcc_all_event_organizers', 20, 3 );