Electronic Mail
Before WWW, electronic mail (E-mail) was the most widely used and may still be the most useful internet application
E-mail suits to the sending of short messages as well as long memos and various files can be sent as its attachments
E-mail differs from the previously discusses internet applications in that it is a "store-and-forward" (rather than "end-to-end") type application
This is because the receiving host may not always be on and reachable
E-mail (just like output to a shared printer) works in a spooled fashion, where outgoing and incoming messages are stored to disk files
Figure 25.1 of Comer represents the structure of an E-mail system