This study investigates how students interpret AI-assisted written communication in a university context. Although AI assistant programs are increasingly used to draft institutional emails, little is known about whether they enhance clarity or undermine trust and perceived professionalism. Using survey data from 194 Vietnamese undergraduates, the study validates four constructs including perceived usefulness, trust, perceived professionalism, and attitudes toward AI assistant programs, and examines their effects on students’ intention to read emails frequently. Results show that students clearly distinguish clarity benefits from credibility concerns, indicating that AI-assisted emails can improve comprehension.