Dear, at this time we are using the RoundCube webmail with the plugin to integrate them with ISPConfig. But what about if we want improve the webmail (and in generale the comunication system of the email customer) with something more organic? For example Zimbra is a pretty cool alternative to Microsoft Outlook and the Google Suite, but at this time there is no easy way to integrate them with the great ISPConfig. Someone know if exist alternative (free or premium) suitable on that purpose? Let us know. Thank you.