isr.co.ro : glossary Bounce To return an e-mail message to the sender without delivering it--usually because the address is incorrect, insufficient, or outdated. Note, however, that the Internet doesn't guarantee notification when delivery fails. A bounce message is a merely a courtesy. Most systems include both a reason for the bounce and the text of the bounced message. If the address is correct, the bounce could be due to a temporary glitch or shutdown somewhere along the pathway or at the receiving end. The solution in these cases is to send the message again.