A friend recently had the HDD in his MacBook Pro Late 2011 (macOS 10.13.6) replaced with a SSD, and had made a Time Machine backup beforehand.
While helping him with some things in Mail, I noticed the Inbox for his Gmail account had over 2,000 messages in it, and suggested he create a maibox in On My Mac and transfer them them there for safety.
When we tried to copy the messages to the new folder, however, they wouldn’t go into it, which I thought was strange.
Later, I also noticed the Trash on his Desktop had a Recovered Files folder in it that contained a Desktop folder, which seemed empty.
When he emptied the Trash, though, there was a brief message saying that some 2,000 or so files were being deleted.
Back in Mail, his Inbox was now empty, as was the Inbox in his Gmail account accessed via the Web.
Is there any chance the messages from the Gmail Inbox can be recovered from the Time Machine backup?
Also, what exactly happened to cause this?