Spam is unsolicited bulk messaging – mostly email, but also SMS, messengers, comments and social media – sent to large numbers of recipients for advertising, fraud or malware distribution.
How spam works
The name comes from a 1970 Monty Python sketch in which the word “Spam” drowns out all conversation. The first known mass email was sent over ARPANET in 1978 to advertise DEC computers, and the 1994 “Green Card” ads by two lawyers on Usenet made spam a public issue.
Spammers harvest addresses from websites and data breaches, buy lists and send billions of messages through botnets of infected computers, compromised mail servers and accounts, or services on bulletproof hosting. Botnets such as Rustock and Cutwail once produced a large share of the world’s spam. Sender addresses are often forged using email spoofing.
Why spam matters
Beyond wasting time and resources, spam is the main delivery channel for phishing, malware attachments, investment and romance scams, and fake shops. Malware families such as Emotet spread through malicious spam (malspam) with Office documents and archives. Regulations such as the US CAN-SPAM Act (2003) and EU e-privacy rules restrict commercial bulk email.
How to fight spam
- Domain owners should publish SPF (RFC 7208), DKIM (RFC 6376) and DMARC (RFC 7489) records; since 2024 Google and Yahoo require them from bulk senders.
- Use mail filters that combine reputation lists, content analysis and attachment sandboxing.
- Do not reply to spam or click “unsubscribe” links in suspicious messages – it confirms that the address is active.
- Use separate or disposable addresses for registrations and report spam with your mail client’s button.
