The table that holds this info is called email_blacklist and the model that does blacklisting is /apps/common/models/EmailBlacklist.php which also contains a lot of hooks you can hook into from your own extension
@Ankit - It works exactly the same as the global blacklist, so you can add one by one, import multiple, delete one/all etc etc, it's the same. The screenshot is just a short version of how a single record is added.
Ah.. Ok.. I don't want the bounces from individual customers to be added to global blacklist and applied commonly on everyone. That's why disabled the feature. But I really would love to have this feature..