SYMPTOMS

The following error is presented in internet browser when trying to access the MailEnable web mail client or Web administration interface.

Error 403.14 forbidden

The web server is configured to not list the contents of this directory

CAUSE

Microsoft .NET extensiblity (4.5) is disabled under server roles "Web server (IIS)" properties. 

RESOLUTION

Windows 2012:

1. Open Server Manager > Dashboard.
2. Click "2" "Add roles and features".
3. Navigate to "Server Roles" and scroll down the list to "Web Server (IIS)"
4. Expand: Web Server (IIS) > Web Server (IIS) > Application Development.
5. Tick the option for the ".NET Extensibilty 4.5" and follow the prompts to install.