Considering the importance of Internet-based communications in our society, the lack of Instant Messaging (IM) services adapted to individuals with cognitive disabilities who have difficulties using written language creates a situation of exclusion that has a negative impact on their daily lives. To alleviate this situation we present Messenger Visual, an IM service that uses pictograms as the main communication system. Along the paper we introduce the main design aspects of an IM service to support pictogram-based communications, as well as the design and evaluation aspects of an IM client that takes into account both the pictogram-based communication and the user interface accessibility requirements of individuals with cognitive disabilities.