1. Log in webmail by using URLs:
https://www.YourDomain.com/webmail/ or https://www.YourDomain.com:2096
2. Linux Web Mail comes with 2 types of Webmail Interfaces for you to select:
a) Horde
b) Roundcube
3. Select the interface that you wish to use and enable to AutoLoad.
Ensure that the Open my inbox when I log in check box is checked.
4. Once you enable the autoload for either Roundcube or Horde, this interface will be the default interface for every times you log in your Webmail.