You can now drill into a the hard or soft bounce stats for an email deployment and see not only a list of prospects who bounced, but why they bounced. You can then export the prospects and bounce reasons as a CSV.
List Email Screen Shot
One to One Email Screenshot
For a long time, we were afraid that showing bounce reasons would amount to tacit encouragement of blindly emailing to purchased lists (which violates our terms and hurts email reputation). The fact of the matter is we will always have a small portion of our users that need education around why this is a bad idea. However, we should not punish the entirety of our good user base who could use this information effectively because of a few bad apples (you know who you are!).
The next step here would eventually be pushing bounce reasons into the CRM.