You need to first validate if the bounced emails are under category of Hard bounces or soft bounces. if majority of the email ids are under Hard bounce category then you know that there is something seriously wrong with the data quality to which you are sending emails.
However if the emails are shown as soft bounce under the live feed section on panel, then there can be below given possible reasons,
1. These emails may not have been delivered because of the temporary reasons like mailbox quota full..etc. we may re-try to deliver the emails to these ids at regular intervals basis the error response.
2. There can be spam filters configured on the MX server of the recipient domain due to which mails may get rejected. You can check the remarks section basis which you can identify the exact reason for email delivery failure.
In case of any help required to understand this better, you can always buzz us on 24X7 chat or write to us on our our helpdesk email id.