There are two main types of Internet email systems: webmail and POP3. Webmail, as the name implies, makes use of a web browser to read, compose, send and manage your mail. POP3 email makes use of a POP3 email client to download your email from a server housing your email mailbox. The main difference between a webmail system and a POP3 email system is that for the former, generally, you have to be online to the server housing your mailbox to access and manage your mail. For the POP3 system, you need to be online to the server only to download your mail, after that you can go offline to read, reply and manage your local mail storage. You only need to go online again when you want to send out your email.
In addition to having a webmail account somewhere on the Internet, webmail needs only a web browser and Internet access to work. Examples of popular webmail services are those from Yahoo and Hotmail. Most ISPs also offer webmail services in addition to their traditional POP3 email services.
To use POP3 email you will need to have a POP3 email client software running on your computer. Both Evolution and Mozilla Mail support POP3 email. In addition, you will also need to know the name of the computer on which your POP3 mailbox is located - the POP3 server, as well as the name of the computer which allows you to send out (relay) mail through it - the SMTP server.
Of course you will need to know your Internet email address irrespective of whether you are using webmail or POP3 email!
Since the usage of webmail involves using your browser mainly, we will not dwell on this form of email anymore here. Instead we will be looking at the POP3 setup and usage of Evolution and Mozilla Mail.