Web-based self-management support systems SMSS, can successfully assist a wide range of patients with information and self-management support. O or as a stand-alone service, are e-messages. This study describes how one component of a multi component SMSS, an e-message service, in which patients with breast cancer could direct questions to nurses, physicians or social workers at the hospital where they were being treated, had an influence on safety and continuity of care. Ninety-one dialogues consisting of 284 messages were analysed. The communications between patients and the healthcare team revealed that the e-messages service served as a means for quality assurance of information, for double-checking and for coordination of care. We give examples of how an e-mail service may improve patients' knowledge in a process of taking control over their own care - increasingly important in a time of growing complexity and specialization in healthcare. It remains to be tested whether an e-message service can improve continuity of care and prevent or mitigate medical mishaps.