I don't want to sound like a tinfoil hat theorist. But... their previous mail transaction service is no longer free, and it's expensive. So they could've switched to mailjet and registered it to the ip.
Nothing, the fact that you can ping the ip by hostname doesnt mean its still used for server. Could be resold or whatever.
Oh well... to make it easier for you folks... fact u can ping hostname and saying its a proof for server to be up is like saying your long dead relative is still alive because his house is still standing.