SP Mail Client is installed as any other standard Joomla! extension, from Extensions Manager by uploading the installation zip file.
Contacts (Address Book)
First thing to configure is to create a new contact's category from your back end->Contacts->Categories. That should be the the category where contact's (address book) for each user will be saved. Note that each user can view only hist contacts and not any other.
Then go to SP Mail Client->Options and choose the category as below image.
In General Options you can also define the various class on how the emails view appears. Keep in mind that the defaults are bootstrap compatible.
The second important thing to do is to define security. The access to the component is defined by the standard Joomla! Access Control List (ACL), for maximum security and compatibility. For example, if you plan for your registered users to use the component in front end we recommend below settings:
You may also decide to create different categories to control different user groups. For example a different account for each of your companies dpts.
Front End Menu
To provide access to front end just go to menu manager and add a new menu item for SP Mail Client.
Now your new webmail client is ready for use!!!