How does that work for the corresponding copy on the other end if they’re using a regular computer? Won’t their computer have a copy? Won’t the server for their ISP?
Not if it was sent to and email on her home-brew server which the recipient had access to. It could have been read, then deleted off her server. Or cleverer yet, she saved it as a draft on her server and someone read and deleted it without it ever being sent.
I have no idea.