What does email spoofing typically involve?

Email spoofing primarily involves forging an email header to misrepresent the source of the email. This technique allows attackers to make it appear as though the email is coming from a trusted source or an individual known to the recipient, thereby increasing the chances of the recipient taking the intended action, such as clicking on a malicious link or providing sensitive information. By manipulating the sender's email address and other header information, spoofers can deceive individuals into thinking they are communicating with a legitimate entity. This tactic is often employed in phishing attacks and can lead to significant security risks for individuals and organizations if proper precautions are not observed.

The other options describe different aspects of email-related activities but do not accurately capture the essence of email spoofing. For example, sending illegitimate emails for personal information theft is more reflective of phishing tactics but doesn’t specifically highlight the forgery of email headers that is central to spoofing. Overloading an email server describes a denial-of-service attack, which is unrelated to the alteration of email identities. Lastly, the accidental use of "Reply All" does not involve any deception regarding the sender’s identity and is more about user error than malicious intent.