Emil Leong on Twitter’s blog:

Last year we began testing a quality filter setting and we’re now rolling out a feature for everyone. When turned on, the filter can improve the quality of Tweets you see by using a variety of signals, such as account origin and behavior. Turning it on filters lower-quality content, like duplicate Tweets or content that appears to be automated, from your notifications and other parts of your Twitter experience. It does not filter content from people you follow or accounts you’ve recently interacted with – and depending on your preferences, you can turn it on or off in your notifications settings.

This is a feature of verified accounts. It shouldn’t have been. Twitter should have given everyone access years ago, but hopefully this will help at least a few with abuse issues. Users will also get an option to only get notifications from people they follow.