I would guess that Costa means the invitations had an associated calendar entry and they deleted the calendar entry. Deleting emails would definitely be pretty creepy, but I don't know if I've ever heard of that happening.
Deleting email messages is 100% a thing. I saw it happen myself (and confirmed with coworkers) at one unicorn I worked at.
Oh, that’s definitely possible. I didn’t think of that. Thanks 'SpicyLemonZest.
It'd be pretty hard to prove or even notice. It's probably happened, the corporate world is too big, but it may not be common.
I witnessed instances in which IT was mandated to delete emails from the server in order to stop a certain piece of information (salary info sent accidentally to a large distribution list). It did not go well, of course, because of POP3. It was pretty hilarious actually seeing people forwarding the email repeatedly. But with a calendar entry, it's a different story as it's centralized.