How are bounced emails handled? What happens if emails can’t be sent?
Bounced emails or bad email addresses that cannot be sent to successfully are marked in your list as being hard bounced. A hard bounce address is a bad address that we cannot mail to successfully because the mailbox or domain no longer exists. The system will not send to any email addresses flagged on your list as hard bounced.
If you export your list to a .csv file and choose to include the status field, these records are marked as "HB" (Hard Bounced) in the status field.