Social engineering is a tactic used by attackers to manipulate individuals into divulging confidential information, such as passwords. In this scenario, the attacker is impersonating a colleague by using a similar email address with a missing letter, attempting to trick the employee into revealing sensitive information.
References: Understanding Cisco Cybersecurity Operations Fundamentals (CBROPS) course and materials provide insights into various types of cybersecurity threats, including social engineering, and how to recognize and respond to them.