Node Cookbook - Third Edition

How it works...

SMTP is based upon a series of plain text communications between an SMTP client and server over a TCP connection. The smtp-protocol module carries out these communications for us.

When we call the createServer method, we pass an event handler that is passed a request object (req). This object is an event emitter (it inherits from the core events module EventEmitter constructor). We listen for to, message, and error events.

The to event supplies two arguments to the handler callback (our filter function). The first argument is the full recipient address, the second (named ack) allows us to accept or reject the incoming message.

Our filter function uses parameter object deconstruction to pull out the accept and reject functions ...