Mailing lists provide a rich set of data that can be used to improve and enhance our understanding of software processes and practices. This information allows us to study development characteristics like team structure, activity, and social interaction. In this paper, we perform an exploratory study on the GNOME project and recover operational knowledge from mailing list discussions. Our findings indicate that mailing list activity is driven by a dominant group of participants, that it is greatly connected to development activity, yet influenced by external factors like market competition. Our results provide a broad picture of the central role played by mailing lists in open source projects.