One of the more annoying features of the Joomla content component is that it provides an easy way for spammers to get hold of your author emails using your articles feed. Even if you do not publish any feeds on your site Joomla will automatically generate a feed of your featured articles and article categories. Armed with a basic knowledge of how Joomla URLS work a spammer will find it easy to get hold of this information.
For example most sites that use the Joomla content component will have a home page that consists of a blog listing of the featured articles: in that case all that the spammer will need to do is to add '?format=feed' to your site url. Try it yourself and you will likely see what I mean. If you right-click the generated page and view the source you will probably see that it displays your email address.
One way to stop that is to change the site configuration to use the site email instead, so that at least the author emails are not exposed, but this is not always a good solution, because you may not want your site email exposed either. You may want to use your site email address to do things like actually contact people, and don't want to get a lot of spam.
The plugin is compatible with Joomla 2.5 and 3, and will work with feeds generated by the Joomla content component. It may also work with other RSS feeds if they work by using the Joomla core document feed type.
You can download the plugin here: https://www.spiralscripts.co.uk/joomla-plugins/email-hider-plugin-detail.html