编写节点。js流到字符串变量中

I'm hacking on a node.js program that captures SMTP mails and acts on the mail data. The 'smtp-protocol' node library provides the mail data live as a stream, and as a node.js newbie I'm not sure how to write that stream into a string variable. I currently have it writing to stdout using the line:I'm hacking on a node.js program that captures