Re: Was it a test?
Not really hard to send stuff from 895M addresses; you can build programs that send it from just over 4 billion addresses. Now; if they were sending it from more than 5 billion addresses and using IPv4 then I'd be impressed.
I'm surprised source IP filtering is still not in yet (and yes I'm quite aware of some of the pitfalls of it). Doesn't make sense for consumer type lines and for the vast majority of commercial ones too.