Falsifying e-mail to spread false information is a common method of cyberattack and may be abused for phishing attacks, fraud, or spreading false information. The following are some common technical methods and their principles, but please note that this information is for defensive and educational purposes only, and any illegal behavior is not advisable. --- ### **1. SMTP protocol forgery** -**Principle**: SMTP (simple mail transfer protocol) itself does not enforce the verification of the sender's identity. An attacker can send mail by directly connecting to a mail server (or a self-built server) and falsifying the sender's address (such as`From: president@whitehouse.gov `). -**Defense**: Use the **SPF (Sender Policy Framework)**, **DKIM (DomainKeys Identified Mail)** and **DMARC (Domain-based message Authentication)** protocols to verify the legitimacy of the sender's domain name. --- ### **2. Header Manipulation (Header Manipulation)** -**Principle**: The `From`,`Reply-To`, or'return-Path` fields in the header of the message can be manually modified to make the recipient mistakenly think that the message comes from a trusted source. -**Defense**: Check the full path of the message header (view the original message) to identify whether it contains a suspicious IP or server. --- ### **3. Domain Spoofing (Domain Spoofing)** -**Principle**： -**Approximate domain name**: Register a domain name similar to the real domain name (such as`paypai.com 'Instead of`paypal.com `). -**Homograph Attack**: Use Unicode characters to disguise domain names (such as`аpple.com `, the first letter is Cyrillic). -**Defense**: Carefully check the spelling of the domain name and enable the “Show real sender address” function of the mail client. --- ### **4. Phishing email generation tool** -**Principle**: Attackers use open source tools (such as **Swaks**, **PhishLabs**) to automatically generate fake emails, and even imitate corporate email templates. -**Defense**: Train users to identify suspicious links or attachments, and deploy anti-phishing filters for mail gateway. --- ### **5. Man-in-the-middle attack (MITM)** -**Principle**: Intercept or tamper with the data during the transmission of the message (for example, in public Wi-Fi), modify the content of the message and then forward it. -**Defense**: Use **TLS encryption** (Mail transport layer security protocol) to avoid processing sensitive mail on unsecured networks. --- ### **6. Fake mail client or service vulnerability** -**Principle**: Exploit vulnerabilities in mail clients (such as Outlook and mobile applications) to bypass sender verification logic. -*****: Keep the mail client and plug-ins updated to the latest version. --- ### **7. Hijack a legitimate account** -**Principle**: By stealing a password or using a weak password to log in to a legitimate email account, you can directly send malicious emails as your real identity. -**Defense**: Two-factor authentication (2FA) is mandatory, and account login logs are reviewed regularly. --- ###**Summary of defense recommendations** 1. **Technical level**： -Configure SPF, DKIM, and DMARC records for the domain name. -Use enterprise-class anti-spam solutions (such as Proofpoint, Mimecast). 2. **User education**： -Train users to identify signs of forged emails (such as grammatical errors, urgent threats, etc.). - Avoid clicking on unverified links or attachments. 3. **Legal means**： -Report forgery to mailbox service providers in a timely manner (such as Gmail's “Report phishing” function). --- ###**Important reminder** Forged emails may involve legal risks (such as identity theft and fraud). The content of this article is only for the popularization of knowledge and is designed to help users improve their security awareness. Any technology should be used within a legal and ethical framework.