Add deprecation notice

Author: felixhammerl

README.md

@@ -1,5 +1,16 @@
 # SMTP Client
 
+## DEPRECATION NOTICE
+
+This project is not actively being maintained. If you're sending emails on a node.js-esque platform, please use Andris Reinman's [nodemailer](https://github.com/nodemailer/nodemailer). It is actively supported, more widely used and maintained offers more possibilities for sending mails than this project.
+
+Background: This project was created because there was no option of using SMTP in a browser environment. This use case has been eliminated since Chrome Apps reached end of life and Firefox OS was scrapped. If you're on an electron-based platform, please use the capabilities that come with a full fledged node.js backend.
+
+If you still feel this project has merit and you would like to be a maintainer, please reach out to me.
+
+
+
+
 [![Greenkeeper badge](https://badges.greenkeeper.io/emailjs/emailjs-smtp-client.svg)](https://greenkeeper.io/) [![Build Status](https://travis-ci.org/emailjs/emailjs-smtp-client.png?branch=master)](https://travis-ci.org/emailjs/emailjs-smtp-client) [![JavaScript Style Guide](https://img.shields.io/badge/code_style-standard-brightgreen.svg)](https://standardjs.com)  [![ES6+](https://camo.githubusercontent.com/567e52200713e0f0c05a5238d91e1d096292b338/68747470733a2f2f696d672e736869656c64732e696f2f62616467652f65732d362b2d627269676874677265656e2e737667)](https://kangax.github.io/compat-table/es6/)
 
 SMTP Client allows you to connect to and stream data to a SMTP server in the browser.