You can set up a filter that raises the priority of any message whose subject includes the word Beatles . If you only want to read messages about Paul, you can create a filter that only raises the priority of messages whose subject contains both Beatles and Paul . Some email programs use it as part of a sender ID, so you may accidentally filter out important emails. After you know the text you want to filter, choose what you want the filter to do. Email filters can delete messages, mark them read, change their priority, or sort them into special folders.
Most people use filters to automatically sort new messages into folders and send spam to the trash.