It's possible to display a clickable email address in the hover on mouse over.
After adding hotspot and different points, you can manage "On mouse over" interactivity.
In the "Action type" field, you choose Display HTML content. Then, you select Rich Text Editor and you add your mailto link.
Also, you must clear the "auto hide over content" field to persist content. Then, click update, save and return.
Note: The hover content position shouldn't be positioned on the hotspot. You can change the alignment( Left and Top) via Behavior -> On mouse over.