There are 3 spots to add email addresses for notifications.
1. Main account holder. This is set at sign up, but can be changed by clicking on the arrow next to your name at the top right of the page and then clicking on Profile. This email will receive all notifications for offers and messages for all listings.
2. Under Settings you can add up to 6 additional email addresses to receive all notifications for offers and messages for all listings.
3. On each listings detail page there is a field titled Additional Email Notification. If you add an email address here, it will receive all notifications for offers and messages for that listing, but not all others.