GMail team has recently added a new add-on feature, to improve the productivity of its users. They have introduced Tasks through GMail Labs, which would let you add a new Tasks window. GMail Tasks can be used to keep track of things that need to get done. The Tasks can be directly added from a email by selecting More Actions -> Add to Tasks, after enabling the Task feature.
You can also directly add new tasks need to be done by just clicking in the new line of floating Task window. You can also add the deadline date and a note on the task. In order to use Task feature you need to go to Settings and select the Labs tab and enable Tasks. You can use the + t, key board shortcut (if you enable it already).
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