Installing and Configuring 2Email
You do not want to install the server on every PC.
If you have a server it can be install upon then that's preferable. Else, it needs to be on a PC which will be powered on whenever anyone wants to use the client, for example the teachers workstation.
The server has to be installed into a location which is visible to everyone else and which people have access to. So you could install it onto an area which is already shared or install it and then share out that folder.
The students will need to have full modify permissions to both the share and file security.
Once it's installed it's simple to configure the client PCs. The quickest way is to install the client, open the file explorer to the installation location (which is usually c:\program files\2simple 2email\application or similar) and then edit the two files email.ini and configurator.ini. These files both need to point to the location of the share which contains the server.
For example, the default file reads
Location=C:\Program Files (x86)\2Simple Software\2Simple Email (Sorter)\Server
and you may change it to
Where ever the share is, the path needs to point to the server folder. After you've change the two files and saved them, you can place them in the server folder and copy them down to each workstation rather than having to edit each.