A Bounce is an email that is returned to the sender because it cannot be delivered for some reason.
Leadsius process and group the bounces by type (hard, soft). We have many rules for detecting hard bounces, such as email inactive, email doesn't exist, remote config error etc. Soft bounces are usually temporary issues, such as an email inbox that is full or mail server temporarily unavailable.
If the bounce is a hard bounce, we will not send any more emails. To see statistics for hard bounce go to Analytics > Programs and select your program. Then go to Email and click on Bounce to see the bounced addresses.