You may have noticed an Email Documents option, but have never used this because the button is 'Greyed Out' like this:

The trick is that you'll need to generate the renewal offer letters first > Choose Attach Documents > Generate Documents

Once they are generated > Click the Filter icon  > Now the Email Documents option is available

Note: If you generate your renewal offers and under the Letters column it says "No Letters to print" like below: 

This means the renewal offers haven’t been approved yet and will need to be approved before you can generate the renewal letters