How to use the nodemailer/lib/wellknown.Zimbra function in nodemailer

var nodemailer = require("nodemailer");
var wellknown = require("nodemailer/lib/wellknown");
var settings = require("../settings");

/*
 * Add Zimbra to wellknown mail service so that Nodemailer recognizes it.
 */
wellknown.Zimbra = settings.mailServices.Zimbra;

function mailer() {}

/*
 * Send mail to recipients.
 *
 * All mail options, such as sender, recipients, subject and body, is contained
 * in options argument.
 *
 * Arguments:
 * - options.from: a string, address of sender
 * - options.to: a string or an array, addresses of recipients
 * - options.subject: a string, subject of the mail
 * - options.body: a string, body of mail that recipients can read
 * - options.html: a boolean, indicate whether the body is formatted in HTML
 */