I am a system administrator and when I make the blacklist of our mailserver so strict I delete mails from our customers without any notice, I think my boss will fire me on the spot.
I think they had a problem last week and they had to come up with a quick and dirty solution.
I wonder what happened with the mails I sent. If they where really completely deleted I find that very disturbing. A mail should get a spam score depending on a lot of factors. If a domain does not have DMAC, DKIM and SPF records, I can understand mail sent from that domain is blocked, perhaps even without a notice. But when a mail system doesn't have any reason to distrust the mail other than a self made whitelist, it is bad practice. Hopefully it is something they are working on.