Spam is a generic term covering a wide range of internet-based unethical and unwanted behavior by a small group of individuals seeking profit by absolutely any means. While we all recognize spam when we see it, different types of spam vary widely in terms of strategy used, technical loopholes exploited and internet medium.
Email spam, also known as unsolicited bulk mailing, is the "classical" type of spam. Spammers use a glaring hole in the email protocol to fake the FROM field of an email, so that the only reliable information as to the provenance of the email is the originating IP in the mail headers. Even the IP is sometimes misleading and may not be useful in identifying the criminal. Thus, spammers continue to operate completely anonymously without fear of ever being prosecuted.
According to a
major service provider:
Once upon a time, unsollicited mails (spams, virus, etc.) were mainly an annoyance for users as they had to manually seperate the wheat from the chaff. Nowdays, unsollicited mails volume is so huge it cause real and serious technical issues for mail hosters.
On december 2007, a study concludes unsollicited mails reached 97.13% of mails traffic. This means you had to oversize your mail platform by 34 times to be able to manage unsollicited mails just like regular mails and this is starting to become quite unmanageable. The volume hits all servers, whether they receive mails (MX servers), store them (both on disk capacity and on IO load) or deliver them to users (POP/IMAP servers).
On december 2006 and 2005, studies have concluded there were around 95% and 90% spams in mail traffic (as usual, mileage may vary). Spam traffic grows roughly twice as fast as regular mail (I meant sollicited mails, not spams) and it is more and more difficult to manage/host a mail cluster. Unsollicited mails traffic may be considered as a continuous DoS against mail hosters.
Forum spam aims at raising the profile of a web site by posting links in various discussion forums.
Most forums require users to register using a valid email address. Spammers use a variety of ways, some manual and some automated, to register into various forums so that they can post their spam.