What is the primary characteristic of email spoofing?

The primary characteristic of email spoofing is that it obscures the true email sender. In this context, spoofing involves forging the sender's address on an email so that it appears to come from a different person or source. This manipulation can be used for various malicious purposes, such as phishing, where attackers aim to deceive recipients into believing they are communicating with a legitimate entity. By disguising the sender's identity, spoofing can effectively trick the recipient into taking actions like providing sensitive information or clicking on harmful links, making it a significant security concern in the realm of email communications.

The other options do not accurately describe email spoofing. Forwarding emails to all contacts refers to a different action that does not involve deception about the identity of the sender. Copying emails sent from a specific user would also not involve obscuring the sender's identity, but rather duplicating communications from that individual. Modifying email routing logs is a technical alteration that may occur in various types of email manipulation but is not the defining characteristic of spoofing itself.