Software: Operating Systems, Network Traffi c, and Applications 䡲 173
E-Mail
E-mail has become the predominant means for people to communicate electronically. Each e-mail
message consists of a header and a body. e body of the e-mail contains the actual content of the
message, such as a memorandum or a personal letter. e header of the e-mail includes various
pieces of information regarding the e-mail. By default, most e-mail client applications display only
a few header fi elds for each message: the sender’s and recipient’s e-mail addresses, the date and time
the message was sent, and the subject of the message. However, the header typically includes
several other fi elds, including the following:
Message ID
Type of e-mail client used to ...