In addition to placing labels on your emails you can also file these against projects, place reference labels and tasks. The tasks allow you to manage work that needs to be performed by selecting Next, Action, Someday, Waiting On... or you can create your own items.
They also suggest a good way to work with email with the main recommendation is to empty your email inbox and the only emails left will relate to work that needs to be performed.
The product is FREE however the additional functions for US$24 is worth it. The ability to schedule a deadline date is important.