We have created and evaluated a novel mobile messaging app named Curtains Messenger. The app has been designed to support synchrony in messaging. It does this by requiring users to be in the app at the same time as each other in order to send, receive and read messages. This design is contrary to typical apps where messages can be sent and read asynchronously at an individual's convenience. We have conducted a field trial in which 15 users installed the app on their own devices and used it in the wild. We present a qualitative analysis of interviews with the participants following the trial. The findings address how the app was used, how synchrony affected conversational flows, how synchrony raised issues of attention and intimacy, and what issues users faced in the practical work of conducting synchronous messaging. This work demonstrates how core concepts in the study of cooperative work such as a/synchrony can be drawn upon to reconsider taken-for-granted design features of mobile applications and the lived experience of communication.

Text messaging has long been a popular activity, and today smartphone apps enable users to choose from a plethora of mobile messaging applications. While we know a lot about SMS practices, we know less about practices of messaging applications. In this paper, we take a first step to explore one ubiquitous aspect of mobile messaging -- messaging history. We designed, built, and trialled a mobile messaging application without history named forget-me-not. The two-week trial showed that history-less messaging no longer supports chit-chat as seen in e.g. WhatsApp, but is still considered conversational and more 'engaging'. Participants expressed being lenient and relaxed about what they wrote. Removing the history allowed us to gain insights into what uses history has in other mobile messaging applications, such as planning events, allowing for distractions, and maintaining multiple conversation threads.