The landscape of malicious emails and cyber social engineering attacks in general are constantly evolving. In order to design effective defenses against these attacks, we must deeply understand the Psychological Tactics (PTacs) and Psychological Techniques (PTechs) that are exploited by these attacks. In this paper we present a methodology for characterizing the evolution of PTacs and PTechs exploited by malicious emails. As a case study, we apply the methodology to a real-world dataset. This leads to a number insights, such as which PTacs (PTechs) are more often exploited than others. These insights shed light on directions for future research towards designing psychologically-principled solutions to effectively counter malicious emails.