Short for e-mail server provider, an ESP is a company or Internet site that offers a service of sending and receiving e-mail to users. The ESP provides an e-mail address and a web portal that allows users to access their received e-mails.
The username chosen when a person first signs up for service often becomes the first part of their e-mail address.
Popular e-mail providers including Outlook.com (formerly Hotmail), Gmail, Yahoo! Mail, and Apple Mail. These and other providers offer their e-mail service at no cost to their users. Some ESPs also provide advanced functionality for a small fee, paid either monthly or annually.