This resource focuses on error analysis in professional correspondence, specifically designed to help students understand the importance of language register in workplace communications. The document outlines an objective where students learn to identify informal and inappropriate language choices in a sample email sent to a library manager regarding an internship request. Activities such as the 'Worst Email' Challenge prompt students to critically analyze casual phrases and symbols that undermine professionalism, reflect on appropriate language adjustments for different audiences, and understand the hierarchy of language formality (register). The resource also features a comparison of casual versus professional language, encouraging discussions about the impact of language choices on sender credibility. It concludes with self-assessment opportunities, allowing students to gauge their confidence in identifying appropriate writing styles for various professional contexts.