How to add a custom skin for Roundcube?

Question

How to add and apply a custom skin for Roundcube in Plesk?

Answer

The skin must be manually uploaded and selected using the command line.

1. Connect to the server via SSH

2. Create a folder inside /usr/share/psa-roundcube/skins/ and place the skin files inside

3. Edit /usr/share/psa-roundcube/config/config.inc.php and enter the skin name

   $config['skin'] = 'custom_skin';