The Custom Sender plugin is an addition to the Email Before Download (version 3.3) plugin. It enables you to easily set up the sender’s name and e-mail address through a simple interface. So instead of ‘WordPress wordpress@your-domain.com‘ you can set up your or your company’s real name and e-mail address as the sender.
In order for this plugin to work you will need the Email Before Download (version 3.3) plugin and it’s dependencies. Without that it will not work, and doesn’t even do anything.