Since I am still in my pre-installation phase for my new rootserver, I was just wondering, which webmail app would fit best for my planned ISPConfig 3 setup. There are quite some projects around, from which AtMail, SquirrelMail, RoundCube and IlohaMail seem to be some popular ones. On first sight I find AtMail the most attractive one. Is there a recommended webmail app for ISPConfig 3? In what way do the install instructions differ from old documents for ISPConfig 2 (as found at the bottom here)? I remember to have stumbled over an extension for ISPConfig 3, which automatically enabled the access to the webmail app through any hosted domain, so that the webmail app only needs to be installed once on the server, and not in each client's webspace individually (if the clients are comfortable by using the choosen webmail app by the server administrator), but I don't remember the details any more. I think this is what I like, so having webmail.exampledomain1.tld webmail.exampledomain2.tld webmail.exampledomain2.tld all just leading to the chosen webmail app. Is this reasonable? And how to do it the easy way?