Information Technology Reference
In-Depth Information
Figure 6.5
When Gina's message to Dan fails on its fi rst attempt, the SMTP
protocol can route through an alternate network path to reach Dan's server.
highly mobile. However, access to e-mail relies on many transfers of each
message from one server to the next, and an ongoing delivery attempt
may take several days before the last SMTP server determines that a mes-
sage is ultimately undeliverable. During this time, the sender knows only
that a message is in transit, and the recipient has no way to know of its
pending arrival unless alerted through other means. Additionally, users
may only check targeted e-mail addresses on an infrequent basis or may
receive such a volume of messages as to obscure an important item in the
midst of hundreds or thousands of offers for mortgage rate improvement,
physical enhancement, and other forms of common spam.
Note:
The term “spam” refers to the electronic equivalent to junk mail.
Analysis of network traffic identifies more than half of all electonic mes-
sages as falling in this category, with some studies showing this to be pos-
sibly as much as 90% of all e-mail or more. The term “spam” was coined
from a humorous skit by the British comedy troupe, Monty Python, in
which Norsemen kept drowning out the principal conversation by chant-
ing “spam” over and over. The association was made because the vol-
ume of unsolicited e-mail has become a problem for servers that must
store these messages and for users who must wade through thousands
