It would be nice if something like automx.org was build in to Smartermail.

automx makes setting up a mail account easy. All your users need to provide is real name, mail address and password. Their mail client and automx will safely handle the rest.  

It generate a .mobileconfig that Apple users can open in safari and are then prompted to install the e-mail settings. Also handle Thunderbird autoconfig, but for Thunderbird it might be easier to base on the autodiscover function.