My company just recently sent out a series of emails to a list of leads. Unsurprisingly some of our emails were bounced. When I went into the results to see who was bounced I was able to see that some of the bounces were bounced due to a spam blocker. It would be helpful if you could have a report created that gives information on specific reasons for bounces (i.e. invalid email, marked as spam by lead, blocked as spam by lead's content filter, etc...).