Also known as Electronic Mail, email addresses are imperative for reliable correspondences, and regular communication between 2 or more people. The host is usually the one responsible for providing you with email services. All email addresses are user@domain or user@sub.domain, however email addresses from subdomains, while they may work aren’t at all common. Every domain technically has unlimited email addresses within the confines of the internet rules regarding addresses. Therefore, you can have frank@fsp.fyi, and there could also be frank@fsp.ws – both of these addresses are unique, and different.