Emotion expression in text-based instant messaging (IM) has received little empirical scrutiny. The emotional message cues people use to express their different emotions in IM communication and how their personality traits affect those cues are the main focus of this study. Results of a preliminary study in IM suggest that in stressful situations people apply significantly fewer vocal spelling emotional cues than in non-stressful situations. There is also a significant relationship between conscientiousness as a personality trait and use of lexical surrogate emotional cues in this type of communication. Our proposed study expands upon preliminary data to uncover more significant differences among the emotional message cues people use to express different emotions in IM, including the role of relevant personality traits. Identifying how users express emotions in IM assists researchers and designers in focusing on the users' emotional needs and results in the improvement of emotional communication strategies in IM.