Email has scaled our ability to communicate with large groups, but has not equivalently scaled our ability to listen and respond. For example, emailing many people for feedback requires either impersonal surveys or manual effort to hold many similar conversations. To scale personalized conversations, we introduce techniques that exploit similarities across conversations to recycle relevant parts of previous conversations. These techniques reduce the authoring burden, save senders' time, and maintain recipient engagement through personalized responses. We introduce MyriadHub, a mail client where users start conversations and then crowd workers extract underlying conversational patterns and rules to accelerate responses to future similar emails. In a within-subjects experiment comparing MyriadHub to existing mass email techniques, senders spent significantly less time planning events with MyriadHub. In a second experiment comparing MyriadHub to a standard email survey, MyriadHub doubled the recipients' response rate and tripled the number of words in their responses.

Social costs and limited reach inhibit our use of social capital to solicit help. However, individuals are not the only holders of social capital: groups also possess reputations and social capital, and are often prepared to vouch for their own members. In this paper, we design methods for mobilizing this collective social capital in sociotechnical systems, enabling an individual to ask a trusted group whether it is willing to invest its reputation in doing them a favor. We instantiate this concept with Founder Center, a web platform in which members of a local entrepreneurship accelerator ask the accelerator community to collectively make them introductions to potential funders. In a field experiment, enabling access to collective social capital in this community nearly doubled the odds of members making a social capital request. Requests fulfilled utilizing collective social capital were at least as effective as ones utilizing traditional interpersonal social capital.