Some legal business companies advertise their products or services using spam. They can send it out on their own, but more often they order it to those companies (or individuals) that specialize in this.
The attractiveness of such advertising lies in its relatively low cost and large coverage of potential customers.
With the help of spam, they often advertise products that cannot be reported in other ways, such as weapons, pornography, drugs with restricted circulation, stolen information (databases), counterfeit software, etc.
Sometimes spam is used to lure money from the recipient of the letter. The most common method is called «Nigerian Letters», because a large number of such letters came from Nigeria. Such a letter contains a message stating that the recipient of the letter can receive a large amount of money, and the sender can help him with this. Then the sender asks to transfer him some money under the pretext of, for example, paperwork or opening an account. Scamming this amount is the goal of scammers.
Phishing (from the English. Fishing - fishing) - another way of fraud by cheating users. It is an attempt to lure the recipient of the data that can be used to obtain benefits: his credit card numbers or passwords for access to online payment systems. Such a letter is usually disguised as an official message from the bank administration. It states that the recipient must confirm the information about himself, otherwise his account will be blocked, and the address of the site (owned by spammers) with the form to be filled out.
Among the data that you want to report, there are also those that are needed by scammers. In order for the victim not to guess about the deception, the design of this site simulates the design of the official website of the bank.
Due to the widespread nature, spam mailings make it difficult for information systems and resources to work, creating a useless load for them.
Network users are forced to spend time every day processing unprofitable advertising messages, and spam brings inconvenience to providers due to increased load on mail servers and communication channels.
To combat spam, anti-spam filters are used, which can be installed both on users local computers and on the provider's mail servers.
Anti-spam filters analyze the content of the letter or try to identify the spammer by e-mail. If a letter is classified as spam, it can be marked, moved to another folder, or even deleted.
To make automatic filtering more difficult, spam messages are often distorted, numbers that are similar in style are used instead of letters, Russian letters are replaced with Latin letters, and spaces are added in random places.