In the previous chapter, the notion of contextual constraint was introduced, briefly described and divided into user- and interface-related. The former was addressed in that chapter, covering several demographic variables that influence emoji utilisation both qualitatively and quantitatively: age, gender role, cultural background, ethnic origin, personality and relationships. This chapter in turn focuses on the latter, i.e. interface-related constraints. In any case, although both types of contextual constraints exist prior to any internet-mediated interaction and hence do not appear to be an inherent object of pragmatic research, their role in the greater or lesser success of internet communication makes their analysis relevant when it comes to determining why online communication (and more specifically emoji-centred communication, as addressed in this book) ends up being either satisfactory or fruitless.