Settings > Emails > Booking Email Templates > Email events admin) * as receiver when Resend button is clicked */ add_filter ('em_mailer_send_parameters', 'my_em_mailer_send_parameters', 10, 1 ); function my_em_mailer_send_parameters( $parameters ){ if ( $_REQUEST['action'] == 'booking_resend_email' ){ $admin_emails = str_replace(' ','', get_option('dbem_bookings_notify_admin')); $parameters['receiver'] = $parameters['receiver'] . ',' . $admin_emails; } return $parameters; }