Email spoofing is a technique used by cybercriminals to send emails that appear to come from a legitimate source. They manipulate the email header to make it look like the message is from a trusted sender, such as a bank or a colleague. This can trick recipients into opening the email and clicking on harmful links or providing sensitive information. Spoofed emails often contain phishing attempts, where attackers seek to steal personal data like passwords or credit card numbers. To protect against email spoofing, users should verify the sender's address and be cautious of unexpected requests for sensitive information.