If your Vista or Windows 2008 Server has UAC (User Account Control) enabled, then web interface setup will not run unless you execute it with elevated rights, as an administrator.  You will need to do it even if you are logged in as a member of administrator group.

Normal executables can be executed with elevated rights by right clicking them, and selecting Run as Administrator, bu this does not work with Windows Installer (MSI) files, which is our Web Interface installer.

There are several ways of executing the MSI file with elevated lights.  One of the easiest ones is to save it in some directory, e.g. c:\temp, then click the Start button, in the Start Search... box type cmd, and press Ctrl - Shift - Enter.  The command window will open in the administrator mode.  Change to the c:\temp folder, and execute WebMailSetup.msi.

Sometimes there is an access rights problem with the App_Data folder. This error occurs when the user, under which your web server is running does not have sufficient rights to write into your WebMail folder.

The easiest way to solve this problem is to add that user to the list of users, and give it full rights to access your WebMail folder.   The user, under which your web server is running is Network Service for Windows 2003 or later, or ASPNET for Windows XP or earlier.

Follow these steps:

• Run Windows Explorer;
• Navigate to folder, where WebMail application is located (by default, it is c:\Inetpub\wwwroot\) click WebMail folder, select Properties, then Security tab;
• Click Add button;
• in the Select Users or Groups window, under Enter the object names... box type either Network Service, or ASPNET, depending on your Windows version (see above), and click OK;
• Allow to the user Full Control;

On Windows 2008 server, in some cases, you may have problems with so called Integrated Managed Pipelining mode. You will need to switch the WebMail application to the Classic .NET Application Pool... To do it:

• Run IIS Manager from Control Panel - Administrtive Tools;
• In the Connections panel, navigate to the WebMail application in the folder on the web site where you installed it
• Click Advanced Settings on the right panel;
• In the Application Pool field, change the value of DefaultAppPool to Classic .NET AppPool;