When you are distributing a newsletter you also need to add a link to an opt-out form. To see how to create an opt-out form click here.
To add the opt-out form to your subscriber options text you simply right click on the footer widget, mark the text and click on the insert link button.
Then you add the unsubscribe tag. Protocol should be set to <other> and the URL should have the merging code [unsubscribe].
Under Style you can choose what from should be attached to the merging code.
Click on the Save button when you are done and you are ready to distribute.