A client of mine who would like to avoid a server upgrade (mainly for mail) asked if there’s any way to set up a computer to download all the mail locally after 14 days. He wants the mail available to his employees on their phones and tablets for that long in case they need it, but thereafter archived on one machine in the office to get it off the server.
I know any POP3 client can do this for inbox mail, but I’m not aware of any way to download Sent, Trash, etc.
OS doesn’t matter because this would be a machine dedicated to that one purpose. It doesn’t necessarily need to be a client, either. It can be another server accessible via a client when archived mail needs to be accessed.