How to centralize CAD data through LAN

Our small organization handles important data from 23 computers. Now, we are currently using CAD for all of those computers through LAN. We know that 23 computers are too many to be handled. Thus we decided to look for a solution that can centralize our important data. At the same time, we also like to have an additional feature to our communication server.
We would like to have an automatic back up on our incoming and outgoing emails for documentation purposes. Kindly give us your best opinions on what to do or what software to have considering our requirements.
