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Vol. 1 · Ed. 2026
CyberGlossary
Entry № 1071

Spam (Email)

What is Spam (Email)?

Spam (Email)Unsolicited bulk email sent indiscriminately to many recipients, typically for advertising, fraud, malware distribution, or as a delivery vector for phishing.


Spam is unsolicited bulk email (UBE) sent to recipients who never requested it, named after the 1978 ARPANET DEC marketing message and popularised by the Monty Python sketch. Modern spam ranges from cheap product advertising and pump-and-dump stock scams to phishing, malware delivery, and BEC pretexting. Botnets like Cutwail and Necurs historically sent the bulk of global spam from compromised hosts. Defences operate at several layers: SMTP-level rate limits and blocklists (Spamhaus, SURBL), authentication standards (SPF, DKIM, DMARC), content filters using Bayesian and machine-learning classifiers, user-feedback signals, and quarantine policies. Legislation such as CAN-SPAM (US, 2003) and the EU ePrivacy Directive imposes opt-in and unsubscribe requirements on legitimate senders.

Examples

  1. 01

    A botnet sending millions of pharmacy-spam emails advertising counterfeit drugs.

  2. 02

    Spam carrying a malicious Excel attachment that installs Emotet when macros are enabled.

Frequently asked questions

What is Spam (Email)?

Unsolicited bulk email sent indiscriminately to many recipients, typically for advertising, fraud, malware distribution, or as a delivery vector for phishing. It belongs to the Attacks & Threats category of cybersecurity.

What does Spam (Email) mean?

Unsolicited bulk email sent indiscriminately to many recipients, typically for advertising, fraud, malware distribution, or as a delivery vector for phishing.

How does Spam (Email) work?

Spam is unsolicited bulk email (UBE) sent to recipients who never requested it, named after the 1978 ARPANET DEC marketing message and popularised by the Monty Python sketch. Modern spam ranges from cheap product advertising and pump-and-dump stock scams to phishing, malware delivery, and BEC pretexting. Botnets like Cutwail and Necurs historically sent the bulk of global spam from compromised hosts. Defences operate at several layers: SMTP-level rate limits and blocklists (Spamhaus, SURBL), authentication standards (SPF, DKIM, DMARC), content filters using Bayesian and machine-learning classifiers, user-feedback signals, and quarantine policies. Legislation such as CAN-SPAM (US, 2003) and the EU ePrivacy Directive imposes opt-in and unsubscribe requirements on legitimate senders.

How do you defend against Spam (Email)?

Defences for Spam (Email) typically combine technical controls and operational practices, as detailed in the full definition above.

What are other names for Spam (Email)?

Common alternative names include: UBE, Unsolicited bulk email, Junk email.

Related terms