To reduce email bombing from the root, you need to implement multiple layers of defense strategies targeting the source, delivery path, and recipient's email system. Here’s a breakdown with examples and recommended solutions:
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Source-Level Protection (Block Attackers)
- Use IP reputation filtering to block known malicious IPs. For example, if an IP suddenly sends thousands of emails to your domain, automatically blacklist it.
- Deploy CAPTCHA or multi-factor authentication (MFA) on email account sign-ins to prevent bots from hijacking accounts.
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Delivery Path Protection (SMTP Layer)
- Enable SMTP authentication (SPF, DKIM, DMARC) to verify senders. For instance, SPF ensures only authorized servers can send emails for your domain, while DMARC tells receiving servers how to handle spoofed emails.
- Rate-limiting: Restrict the number of emails a single IP or account can send per minute/hour.
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Recipient-Side Protection (Email Server & Client)
- Use email filtering tools to detect and quarantine suspicious emails. For example, flag emails with identical subjects or high attachment volumes.
- Implement challenge-response systems (e.g., temporary email verification links) for unknown senders.
Recommended Tencent Cloud Services:
- Tencent Cloud Anti-DDoS: Mitigates volumetric attacks targeting email servers.
- Tencent Cloud Email Security (SEC): Provides SPF, DKIM, DMARC, and AI-based spam filtering.
- Tencent Cloud WAF: Protects webmail interfaces from bot-driven attacks.
Example: If an attacker spoofs your domain to send spam, DMARC (via Tencent Cloud SEC) will reject or quarantine such emails at the recipient’s server, reducing the impact.