Emoticon usage in computer-mediated communication (CMC) by university staff is potentially a double-edged sword in forming desired impressions in the minds of students, increasing perceived warmth but also decreasing perceived competence of the sender. Existing studies in higher education have provided little understanding of this trade-off. No work has examined effects of, first, emoticon usage on important educational outcomes (student evaluations, task behaviour), and second, potential moderators relevant within education (i.e. job title, institutional prestige, age of sender, assessment level). We contribute to this area of knowledge through three controlled experiments across different educational CMC settings (total n = 848). Generally, we find that emoticon use increases perceived warmth, which outweighs decrease in perceived competence of university staff, in that perceived warmth -- but not competence -- affects student evaluation and task behaviour positively. These findings hold largely irrespective of the moderators explored. Implications for higher education practitioners are provided.