To send e-mail, you need to connect to the Internet and an e-mail application, such as Microsoft Outlook Express or Eudora. The e-mail application connects to your mail server that can forward your mail. The standard protocol used for sending Internet e-mail is called SMTP, an acronym for Simple Mail Transfer Protocol. It works in conjunction with a POP3 (Post Office Protocol) server or an IMAP (Internet Mail Access Protocol) server, which are used to receive e-mails.

When you send an e-mail message, your computer transmits it to an SMTP server using the Internet. The server looks at the e-mail address (like the address on an envelope), then forwards on it to the recipient's mail server using an application called Sendmail. If for some reason, the recipient?s e-mail server is inaccessible, Sendmail periodically re-tries to send the e-mail. If after 4 hours the e-mail has not been delivered, you receive a notification informing you about the problem. If the e-mail cannot be delivered even after 5 days, Sendmail gives up and sends you a failure notification.

When the e-mail is received at the destination mail server, it is stored until it is retrieved by the addressee. To retrieve your e-mails, your e-mail client (such as Microsoft Outlook or Outlook Express) connects to the POP3 or IMAP server and issues a series of commands to download copies of your e-mail messages to your computer.

E-mails can be sent anywhere in the world to anyone who has an e-mail address. Almost all Internet service providers (ISPs) offer an e-mail address with every account.

Initially, when e-mail technology was introduced, only short messages could be sent. Attachments such as formatted documents, photographs etc could not be sent. With the introduction of Multipurpose Internet Mail Extension (MIME) and other encoding techniques, it has become possible to send almost any kind of attachments.