There are a number of us who use Office 365 this week that have seen first hand how Microsoft tends to defend its users from these scammers.
By listing the domain names of the user's company as being infected with Malware. Then going through all of the emails for that user and their company, removing them from their mailboxes and throwing them in to quarantine en mass.
At which point, they then say "Oops, sorry" after a full 2 days of these shenanigans without so much as an explanation as to why, to only then (from last night) remove emails that have been received this week and then redeliver them to the same mailbox, as if the emails have just been sent.
Colour me surprised that no one seems to have covered this monumental faux pas, that's affected a fair number of customers?