This topic defines spam and provides background information.
Spam definition
The Internet Society of China defines spam as email sent without the recipient's permission. It is also sent to many users at once, which affects normal network communication. Spam often contains malicious, false, or disguised sender information. The following are some common features of spam:
Sent in bulk with identical or similar content.
Sent from a forged or spoofed sender address.
Contains non-standard or missing information in the email header. For example, the timestamp is set to a future time.
Contains intentionally added or mixed content to evade detection.
Contains harmful information, such as viruses or phishing URLs.
Illegal or regulated content, such as pornographic emails.
Is likely to annoy users, which leads to reports and complaints.
The dangers of spam
Email is one of the most widely used services on the Internet. Because the Internet is open and information spreads quickly, the flood of spam has become a major threat to users. The main dangers include the following:
Reduced communication service quality: Spam consumes network bandwidth, congests email servers, and reduces the operational efficiency of the entire network.
Disruption to work and life: A large volume of spam wastes a recipient's time and resources. Legitimate emails can be lost in the flood of spam, which reduces productivity.
Information leaks: Phishing emails are increasingly stealthy and dangerous. They can easily cause information leaks for businesses and individuals. This information can then be used for illegal activities such as fraud or theft of trade secrets.
Harm to society: Malicious actors can spread false and harmful information, which seriously threatens social stability.
Damage to an ISP's reputation: Hosts that send large amounts of spam are added to blacklists by international anti-spam organizations. This restricts the host's ability to access websites or send email and damages the reputation of the Internet Service Provider (ISP).
The importance of anti-spam systems
Email attacks against businesses and individuals are on the rise. Because these attacks are profitable, spammers constantly develop new techniques to bypass email filters. An anti-spam system is the first line of defense for a mailbox system, protecting it from these attacks.
Internally, an anti-spam system blocks outgoing spam. This protects the IP reputation for outgoing mail and keeps delivery channels clear, ensuring that your emails are delivered. Externally, the system blocks incoming spam and mail-bombing attacks from other systems. This keeps your mailbox secure and free of unwanted email.