CompuServe treats this situation just like Postal Inspectors. They intercept Email only on court order. Cost makes a hard-wired network among the seven departments impractical and traffic demand isn't that great anyway. Tulip Systems decided to do it by telephone. One computer serves as the master mail server for the network.
Departments call in to the server retrieve or send messages.
On your standard desktop is the last place they belong. My first desktop sprawled over a good part of the work area available. My computer now is in a tower case. It's tucked into part of the knee hole I'm not occupying. I can reach it on the rare occasion I need to insert a diskette.