Hi Tiffani,
Excluded Email records are based on a past email. For example, if you sent a newsletter last month and there was a bounce due to an invalid email for one recipient, if you tried to send to the same person this month, we would record an "Excluded Email" record for this month's newsletter, showing that we had blocked it. If you want to see what happened with a current email and why the emails bounced, you would just view the Email Events for the email. We record the type (bounce) and the reason for the bounce would be in the "Message" field on the Email Event.