SMTP (Simple Mail Transfer Protocol) | POP3 (Post Office Protocol)
Whenever you send a piece of email, your email client interacts with the SMTP Server to handle the sending. When you compose a message and press the send button, here is what happens:- Outlook Express (SMTP client) connects to the SMTP server at mail.howstuffworks.com using port 25 Outlook Express has a conversation with the SMTP server, telling the SMTP server the address of the sender and the address of the recipient, as well as the body of the message The SMTP server takes the "to" address ( jsmith@mindspring.com ) and breaks it into two parts: The recipient name (jsmith) The domain name (mindspring.com) If the "to" address has been another user at howstuffworks.com, the SMTP server would simply hand the message to the POP3 server for howstuffworks.com(using a little program called the delivery agent). Since the recipient is at other domain, SMTP needs to communicate with that domain ...