E-mail spam

(Spam Twitter)-E-mail spam, also known as junk e-mail or unsolicited bulk e-mail (UBE), is a subset of spam that involves nearly identical messages sent to numerous recipients by e-mail. Definitions of spam usually include the aspects that e-mail is unsolicited and sent in bulk. One subset of UBE is UCE (unsolicited commercial e-mail). The opposite of "spam," email which one wants, is called "ham," usually when referring to a message's automated analysis (such as Bayesian filtering).

E-mail spam has steadily grown since the early 1990s. Botnets, networks of virus-infected computers, are used to send about 80% of spam. Since the cost of the spam is borne mostly by the recipient, it is effectively postage due advertising.

The legal status of spam varies from one jurisdiction to another. In the United States, spam was declared to be legal by the CAN-SPAM Act of 2003 provided the message adheres to certain specifications. ISPs have attempted to recover the cost of spam through lawsuits against spammers, although they have been mostly unsuccessful in collecting damages despite winning in court.

Spammers collect e-mail addresses from chatrooms, websites, customer lists, newsgroups, and viruses which harvest users' address books, and are sold to other spammers. They also use a practice known as "e-mail appending" or "epending" in which they use known information about their target (such as a postal address) to search for the target's e-mail address. Much of spam is sent to invalid e-mail addresses. Spam averages 78% of all e-mail sent.According to the Message Anti-Abuse Working Group, the amount of spam email was between 88-92% of email messages sent in the first half of 2010.

Overview

From the beginning of the Internet (the ARPANET), sending of junk e-mail has been prohibited,enforced by the Terms of Service/Acceptable Use Policy (ToS/AUP) of internet service providers (ISPs) and peer pressure. Even with a thousand users junk e-mail for advertising is not tenable, and with a million users it is not only impractical, but also expensive. It is estimated that spam cost businesses on the order of $100 billion in 2007. As the scale of the spam problem has grown, ISPs and the public have turned to government for relief from spam, which has failed to materialize.

Types

Spam has several definitions varying by source.

Unsolicited bulk e-mail (UBE)—unsolicited e-mail, sent in large quantities.

Unsolicited commercial e-mail (UCE)—this more restrictive definition is used by regulators whose mandate is to regulate commerce, such as the U.S. Federal Trade Commission.

Spamvertised sites

Many spam e-mails contain URLs to a website or websites. According to a Commtouch report in the first quarter of 2010, there are "...183 billion spam messages" sent every day. The most popular spam topic is "pharmacy ads" which make up 81% of e-mail spam messages.

Most common products advertised

According to information compiled by Commtouch Software Ltd., E-mail spam for the first quarter of 2010 can be broken down as follows

E-Mail Spam by Topic

Pharmacy 81%

Replica 5.40%

Enhancers 2.30%

Phishing 2.30%

Degrees 1.30%

Casino 1%

Weight Loss 0.40%

Other 6.30%

Blank spam

Blank spam is spam lacking a payload advertisement. Often the message body is missing altogether, as well as the subject line. Still, it fits the definition of spam because of its nature as bulk and unsolicited e-mail.

Blank spam may be originated in different ways, either intentional or unintentionally:

Blank spam can have been sent in a directory harvest attack, a form of dictionary attack for gathering valid addresses from an e-mail service provider. Since the goal in such an attack is to use the bounces to separate invalid addresses from the valid ones, spammers may dispense with most elements of the header and the entire message body, and still accomplish their goals.

Blank spam may also occur when a spammer forgets or otherwise fails to add the payload when he or she sets up the spam run.

Often blank spam headers appear truncated, suggesting that computer glitches may have contributed to this problem—from poorly-written spam software to shoddy relay servers, or any problems that may truncate header lines from the message body.

Some spam may appear to be blank when in fact it is not. An example of this is the VBS.Davinia.B e-mail worm which propagates through messages that have no subject line and appears blank, when in fact it uses HTML code to download other files.