What is Webmail?
Webmail( or web based email) is any email client implemented as a web Application running on a web server. Examples of webmail software are Roundcube and SquirellMail. Examples of webmail providers are AOL Mail, Gmail, Outlook.com/Hotmail.com, Rackspace Wmail and Yahoo! Mail. Many webmail providers also offer email access by a desktop email client using standard email protocols, while many internet service providers provide a webmail client as part of the email service included in their internet service package.
As with any web application, webmail's main advantage over the use of a desktop email client is the ability to send and receive email anywhere from a web browser. Its main disadvantage is the need to be connected to the Internet while using it. Other software tools also exist to integrate parts of webmail functionality into an OS (e.g. creating messages directly from third party applications via MAPI).