Yes you can, In a local area network (LAN) environment, Microsoft Outlook communicates with Microsoft Exchange Server by using remote procedure call (RPC) with Transmission Control Protocol/Internet Protocol (TCP/IP). This method provides quick and efficient access in a corporate network.
However, access to Exchange when you are outside of your organization’s firewall, such as when you are at home or traveling, usually requires a virtual private network (VPN) connection to the organization’s network. A VPN provides you with a connection within an organization’s network and within its firewall. A VPN also enables access to more network services than those required for just e-mail access.