All emails, including attachments, were automatically copied to the boss. And also to an archive. Nothing was deleted.
When sales and the boss wanted to discuss a document that was on the file server, they sent it to each other as an email attachment rather than just linking to it..
Eventually the overnight backup didn't have enough time to run because the multiple email copies were taking so much space. A better backup system was not obtained because it would cost some fairly trivial amount of money (this was a company that made the techs (but not sales) put old printouts back through the printer upside down to save on paper (which meant they had to pay out for a new drum when it got damaged(possibly by paper with a staple being put through))).
When the server died, the latest backup was a month old. It cost a lot of money sorting out all the missing stuff and calming the clients.
A year later, out of interest, I checked with the hardware guy. The latest backup was still that same one, now 13 months old.