Yes. Our system automatically detects hard bounces and tags them as bounced so it won’t send any emails to those addresses in the future. In fact we have a shared data base of invalid addresses and those detected in the import process are tagged as bounced directly. The firs time you send your newsletter Mailrelay will detect failed emails in your data base and tag them as bounced. In future newsletters the system will only send to active subscribers and bounced addresses won’t be send nor charged.