By default, Mogul tables have 3 columns active: Name/Avatar, Last Interaction and Notes. By going to the Settings Page and scrolling down to Customization, you can access the table column editor by clicking "Customize Table Columns".
Custom Column Editor
You can add modify and re-order the existing columns here, as well as add any new columns as well. This editor supports custom fields.
Adding an email column to the table
The Name/Avatar Field cannot be modified or re-ordered, it will always be the first column in the table