Mail Bomb
What is Mail Bomb?
Mail BombAn email-based denial-of-service attack that floods a mailbox or mail server with high volume or large messages to overwhelm storage, processing, or attention.
Mail bombing (email bombing) sends thousands to millions of messages at a target address, often by subscribing the victim to many newsletters and confirmation services. Variants include simple high-volume floods, zip-bomb attachments that explode on antivirus or preview, list-linking (subscription bombing) used to drown out fraud-alert emails after account compromise, and reply-all storms in enterprises. Effects include filled mailboxes, slow or unusable mail clients, missed alerts, and exhausted mail-server resources. Defences: rate limiting per recipient, anti-abuse on sign-up forms (CAPTCHA, double opt-in, IP reputation), spam filters with anomaly detection, separate high-priority alert channels, and automated quarantine for sudden volume spikes.
● Examples
- 01
Subscribing a victim's address to thousands of newsletters to bury a bank fraud alert after stealing their card.
- 02
Sending a zip-bomb attachment that exhausts a mail gateway's scanner.
● Frequently asked questions
What is Mail Bomb?
An email-based denial-of-service attack that floods a mailbox or mail server with high volume or large messages to overwhelm storage, processing, or attention. It belongs to the Attacks & Threats category of cybersecurity.
What does Mail Bomb mean?
An email-based denial-of-service attack that floods a mailbox or mail server with high volume or large messages to overwhelm storage, processing, or attention.
How does Mail Bomb work?
Mail bombing (email bombing) sends thousands to millions of messages at a target address, often by subscribing the victim to many newsletters and confirmation services. Variants include simple high-volume floods, zip-bomb attachments that explode on antivirus or preview, list-linking (subscription bombing) used to drown out fraud-alert emails after account compromise, and reply-all storms in enterprises. Effects include filled mailboxes, slow or unusable mail clients, missed alerts, and exhausted mail-server resources. Defences: rate limiting per recipient, anti-abuse on sign-up forms (CAPTCHA, double opt-in, IP reputation), spam filters with anomaly detection, separate high-priority alert channels, and automated quarantine for sudden volume spikes.
How do you defend against Mail Bomb?
Defences for Mail Bomb typically combine technical controls and operational practices, as detailed in the full definition above.
What are other names for Mail Bomb?
Common alternative names include: Email bombing, Subscription bombing, List bombing.
● Related terms
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Spam (Email)
Unsolicited bulk email sent indiscriminately to many recipients, typically for advertising, fraud, malware distribution, or as a delivery vector for phishing.
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Phishing
A social-engineering attack in which an attacker impersonates a trusted party to trick a victim into revealing credentials, transferring money, or running malware.
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Business Email Compromise
A targeted fraud in which an attacker impersonates or takes over a corporate mailbox to trick an employee into wiring money, changing payment details, or sending sensitive data.
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Email Spoofing
Forging email headers so a message appears to come from a trusted sender, typically to enable phishing, fraud, or malware delivery.