Transactional email is included, email boxes using your domain name are available as an addon for $5 per year. These email boxes are meant to be a cheap and easy way for you to have email using your domain name. If your email is critical to you and your business and or team you may want to consider something like Outlook365, Rackspace mail, or Gsuite.
These are emails sent out by your site for things like password resets, new user registration, orders, etc..
Each email box comes with 2GB of storage, and antivirus and antispam. You can use webmail in your browser or connect your devices and use it on them, these are not to be used for any type of marketing, email blasts, or any other type of mass mailing. Doing so will result in immediate suspension.