Mobile learning (m-learning) is becoming increasingly significant for educators and businesses. Prior research often examines the effectiveness of m-learning; however, it overlooks that learners with different characteristics may respond to m-learning differently. This research examines how learners with different personalities react to m-learning messages. Specifically, it uses the Myers-Briggs Type Indicator (MBTI), which is one of the most widely-used personality instruments, and uses four dichotomies, namely introversion–extroversion, sensing–intuition, thinking–feeling and judgment–perception, to describe learner personalities. We conducted a 10-week study with 217 students. We used MBTI to categorize these 217 participating learners into sixteen personality groups, and sent short text messages to their mobile devices. These messages stimulated them to access lecture materials and to participate in online class discussions. We observed how learners with different personalities responded to text messages, and confirmed that learners of different personalities showed different levels of responses to m-learning messages.