Can you setup the Roundcube vacation plugin in cPanel?
While there are many methods of installing Roundcube plugins, cPanel includes a customized RPM for Roundcube, which we can see here:
# rpm -qa | grep round
This means that if you manually install a plugin, it will likely be removed as part of a future cPanel update. If you wanted to customize Roundcube the best way to do that would be to create a custom RPM, which we have more details about here: