Mail Message Format
When an e mail is sent from one person to another a header containing peripheral information precedes the body of the message itself. This contained information is contained in a series of header lines. The header liens and the body of the message are separated by a blank line. Each header line contains readable ext consisting of a keyword followed by a colon followed by value. some of the keyword are required and others are optional. Every header must have a from header line and a to header line a header may include a subject header line as well as other optional header liens a message header looks like this.
The to field gives the address of the primary recipient. Having multiple recipients is also allowed. The cc field gives the addresses of any secondary recipients. In terms of delivery there is o distinction between the primary and secondary recipients. The terms cc ( carbon copy0 is a bit dated since computers do not use cardoon paper but it is well established. The Bcc( Billed carbon copy) field is like the cc field except that this line is deleted from all the copies sent to the primary and secondary recipients. This feature allows people to send copies to third parties without the primary and secondary recipients knowing this. The next two field from and sender tell who wrote and sent the message respectively. A line containing received is added by each message transfer agent along the way. The lien contains the agents identify the date and data and time the message was received and other information that can be used for finding bugs in the routing systems. The return path field is added by the final message transfer agent and was intended to tell how to get back to the sender.