Example of Email Delivery
A good understanding of email delivery is helpful in understanding the key principles and items presented in the following topics. The provided example is a simplified description of the email delivery process and describes one email being sent. When you send thousands or millions of emails, the process becomes more complex. Siebel Email Marketing is designed to address the issues associated with sending a large volume of emails.
When an email is sent by person A to person B, an attempt is made to deliver the email. The first step in the process occurs when the user clicks Send in his or her email client. The email client tries to initiate a connection to an email server.
When the client has a connection to a Mail Transfer Agent, the Mail Transfer Agent and the client communicate using the Simple Mail Transfer Protocol. The following are important parts of this communication:
One critical piece of this communication involves the transfer of the email message to the Mail Transfer Agent.
Another piece of this communication is the passing of the sender's email address. This email address is often referred to as the SMTP envelope from (or sender) address. The use of the term envelope represents the email content as a letter and the SMTP communication as the envelope used to carry the letter.
If the recipient of the email (person B) has his or her mailbox on this server, then the server drops the email in the box and the job is done. If person B is on another domain, then the Mail Transfer Agent executes a Domain Name Service (DNS) lookup to find the address of another Mail Transfer Agent to communicate with. Another Simple Mail Transfer Protocol conversation occurs and the second Mail Transfer Agent receives the message and delivers it to the mailbox for person. When it is in person B's mailbox, the recipient can retrieve it using another protocol such as Post Office Protocol (POP) and read the message in an email application.