Unable to send emails using Haraka

send_emails.js

var outbound = require('./outbound');

var plugin = this;

var to = '[email protected]';
var from = '[email protected]';

var contents = [
    "From: [email protected]",
    "To: [email protected]",
    "MIME-Version: 1.0",
    "Content-type: text/plain; charset=us-ascii",
    "Subject: Some subject here",
    "",
    "Some email body here",
    ""].join("\n");

var outnext = function (code, msg) {
    switch (code) {
        case DENY:  plugin.logerror("Sending mail failed: " + msg);
                    break;
        case OK:    plugin.loginfo("mail sent");
                    next();
                    break;
        default:    plugin.logerror("Unrecognised return code from sending email: " + msg);
                    next();
    }
};

outbound.send_email(from, to, contents, outnext);