E-mail spam, also known as junk e-mail, is a subset of spam that involves nearly identical messages sent to numerous recipients by e-mail. A common synonym for spam is unsolicited bulk e-mail (UBE). Definitions of spam usually include the aspects that email is unsolicited and sent in bulk. "UCE" refers specifically to unsolicited commercial e-mail.
E-mail spam has steadily, even exponentially grown since the early 1990s to several billion messages a day. Spam has frustrated, confused, and annoyed e-mail users. The total volume of spam (over 100 billion emails per day as of April 2008) has leveled off slightly in recent years, and is no longer growing exponentially. The amount received by most e-mail users has decreased, mostly because of better filtering. About 80% of all spam is sent by fewer than 200 spammers. 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. Much of spam is sent to invalid e-mail addresses. Spam averages 94% of all e-mail sent.
Spam and fraudulent e-mail messages are major issues for computer users and businesses of all sizes. Companies are being forced to commit significant resources to protect their messaging infrastructure and their brand from these abuses, and computer users must work to protect themselves from the influx of deceptive e-mail. Network infrastructure is being taxed. Spam was once just an annoyance, but it has now become the tactic of choice for online deception, fraud, and abuse.
Microsoft Exchange Hosted Filtering, formally FrontBridge Services, is an e-mail filtering service that stops spam and viruses before they reach the corporate network. A global, load-balanced network of data centers ensures reliable e-mail delivery even during the largest spam and virus attacks. A sophisticated, layered e-mail filtering approach improves employee productivity through high spam-capture rates with almost no false positives. Using a managed service model, Exchange Hosted Filtering reduces complexity in the IT environment, frees IT resources for more strategic corporate initiatives, allows for a predictable service payment regardless of increases in spam and virus activity, and eliminates the costs required to scale to increasingly severe messaging threats. Network performance and filtering accuracy are backed by a comprehensive set of service level agreements (SLAs).
To help reduce the negative impact of junk e-mail, Windows Live Hotmail uses SmartScreen technology to provide junk e-mail protection and help identify and separate junk e-mail from legitimate e-mail. The SmartScreen content filter learns from known spam threats and from information provided by Windows Live Hotmail customers who are part of the voluntary Feedback Loop Program (FBL).
The Exchange Server Intelligent Message Filter (IMF) is part of a comprehensive effort to enhance e-mail protection, security, hygiene, and productivity. IMF is designed to combat the influx of unsolicited commercial e-mail and to enable users to distinguish between legitimate e-mail messages and unsolicited spam. Based on SmartScreen technology, Exchange Server 2003 IMF provides server-side message filtering, heuristics-based message analysis, and support for per-message spam confidence level (SCL) ratings.
