An email server allows users to filter, verify and authenticate emails before sending them to the designated recipients. It is possible to set up an email server on your local LAN, by installing the optional Simple Mail Transfer Protocol (SMTP) service in a Windows computer connected to the network. The computer must have Microsoft Windows Server or Internet Information Services (IIS) installed. Once the email server is activated, you can relay email to connected email client applications.
Install the Email Server
Click "Start," then "Control Panel" and double-click "Add or Remove Programs."
Click "Add/Remove Windows Components" in the left pane of the window. Click "Application Server" in the "Components" list, then click "Details."
Click "Internet Information Services (IIS)" from the "Subcomponents of Application Server" list, then click "Details."
Select the check box next to "SMTP Service" from the "Subcomponents of Internet Information Services (IIS)" list, then click "OK." Click "Next," then "Finish." The email server is now set up to be accessed by email clients on your local area network.
Connect an Email Client to the Email Server
Click "Start" on the computer with the email server, then "Control Panel." Click "System" or "System and Security," then "Administrative Tools" and double-click the "Internet Information Services" console.
Right-click on the SMTP server you set up, then choose "Properties" from the pop-up list. Click the "General" tab and enter the IP address of the server on the network. Click the "Access" button, then click "Connection."
Click "Add" and re-enter the server's IP Address, then click "OK." Launch an email client like Microsoft Outlook on any computer connected to your local LAN. Navigate to the email accounts section and change the SMTP protocol to the IP address of the email server. The emails will now go through your email server before being relayed.