Email is *one* way for open source communities to communicate. An even better way is what we're doing over at Indie Web Camp. We intentionally have no email list, instead we use IRC (with web and Slack gateways) for day to day discussion, and anything important gets categorized and archived on the wiki. This leads to better organization of information over the long term (have you ever tried to actually go find something in email list archives?) as well as provides a better medium for quick conversation.