Parts of code to send email on change of a Keystone Model

mailer.js

//mailer.js exports an object that matches what Keystone expects for its Mandrill objects, allowing you to use node-mailer (in this case) for sending email.

var nodemailer = require('nodemailer'),
    smtp = require('nodemailer-smtp-transport'),
    Q = require('q'),
    _ = require('underscore');

if (!process.env.SMTP_USER || !process.env.SMTP_PASS) throw new Error("Expected SMTP_USER and SMTP_PASS env, missing one or both.");

//Also see more node mailer transport options https://github.com/nodemailer/nodemailer
var transport = nodemailer.createTransport(smtp({
    host: '',
    port: 25,
    secure: false,
    ignoreTLS: true,
    auth: {
        user: process.env.SMTP_USER,
        pass: process.env.SMTP_PASS
    }
}));

var mapToResults = function (arr) {
    return arr.map(function (r) {
        return r.value;
    });
};

var send = function (toSend, onSuccess, onFail) {
    var message = toSend.message;
    
    if (!message.to || message.to.length === 0) {
        console.warn("WARNING: No emails found to send mail to.");
        return;
    }

    var messageBase = {
        from: "\"" + message.from_name + "\" <" + message.from_email + ">",
        subject: message.subject + " - " + Date.now(),
        html: message.html
    };

    var sendMessages = message.to.map(function (t) {
        var thisMessage = _.extend({}, messageBase, {
            to: "\"" + t.name + "\" <" + t.email + ">",
            replyTo: "\"" + t.name + "\" <" + t.email + ">"
        });

        return transport.sendMail(thisMessage);
    });

    Q.allSettled(sendMessages).done(function (results) {
        var errors = results.filter(function (r) {
            return r.state !== "fulfilled";
        });
        if (errors && errors.length > 0) {
            console.log("Errors while sending mail.");
            errors.forEach(function (e) { console.error(e); });
            onFail(mapToResults(errors));
        }
        else {
            onSuccess(mapToResults(results));
        }
    });
};

module.exports = {
    send: send,
    mandrill: {
        messages: {
            send: send,
            sendTemplate: function (a, b, c) { }
        },
        templates: {
            render: function (a, b, c) { }
        }
    }
};

Model.js

//Add this to the model that will be sending email
//It doesn't have to form part of the model, but it follows what we see elsewhere in Keystone, e.g. https://github.com/JedWatson/sydjs-site/blob/master/models/Post.js

//Swap out the model name of users to lookup and input your own values for the email


var mailer = require('mailer.js');

//monkey patch in async saves in mongoose 3.x, h/t:http://stackoverflow.com/a/26049430/1592 , https://github.com/Automattic/mongoose/issues/787#issuecomment-56896373
var notifyUsers = function(callback) {
	var postedForm = this;
	// Method to send the notification email after data has been loaded
	var sendEmail = function(err, results) {
		if (err) return callback(err);
        if (!results || results.length === 0) {
			console.warn("WARNING: No admin users found to send sponsorship notification to.");
			return callback();
		}
		async.each(results, function(notifyUser, done) {
			new keystone.Email.send({
        mandrill: mailer.mandrill,
				userName: notifyUser.name.first || notifyUser.name.full,
				sponsorName: postedForm.name,
				sponsorEmail: postedForm.email,
				comments: postedForm.comments,
				subject: '',
				to: notifyUser,
				from: {
					name: 'EMAIL SENT FROM',
					email: 'website@example.com'
				}
			}, done);
		}, callback);
	}
	
	keystone.list({{MODEL NAME TO LOOKUP FOR WHOM TO SEND EMAIL TO}}).model.find().where('sendAnEmail', true).exec(sendEmail);
};

Sponsor.schema.methods.save = function(done) {
    return Model.prototype.save.call(this, function(err, result) {
       if(err) {
           console.error(err);
           return done(err, result);
       }
       
       var fns = [notifyUsers.bind(result)];
       return async.series(fns, function(err) {
           if (err) console.error(err);
           done(err, result)
       });
    });
};