Definitely anything on your work email account is property of your employer, and they can access it at any time.
Speaking of customer email addresses, when I glance over the list, I’m always just baffled to see work domains–especially schools and government because not only are those your employer’s property but also public record.
Do you really want taxpayers knowing where all you shop online?! 
I wonder if those entities would also fake a malware alert, to investigate? Or was Amazon just that desperate?
As it said in the article, Amazon accused defendants of 8 things in this civil suit, but only 1 thing actually had enough evidence to be allowed to proceed.