I didn't know that their emails were public domain. This is very cool. It must be a treasure trove of data. I wonder if they can really deliver these this way

I didn't know that their emails were public domain. This is very cool. It must be a treasure trove of data. I wonder if they can really deliver these this way though. I would think their IP addresses would get black-listed for spamming almost immediately. Anybody know what stack they're using for delivering thousands of emails a day?