Recently I had the opportunity to develop and integrate an SMTP Email Server into a more extensive full-stack application. Today we will reference the code from my solution for this tutorial.
We'll primarily be using Express and Node to create this server. We’ll also integrate Nodemailer to construct a mailable object and Gmail SMTP Server to deliver our emails free of charge.
The full codebase can be viewed here:
Before we start coding, we should quantify the expected functionality of our Express mail server. We can always refer back to this list later if confusion develops.
- Establish API routes to a contact form on the frontend.
- Receive user data from these routes upon form submission.
- Format a mailable JSON object with the data received.
- Construct a transport function with Nodemailer in preparation for delivery.
- Obtain authorization from Gmail using credentials stored in the server.
- Call the transport function, prompting Nodemailer to handoff the email object to the Gmail SMTP Server for delivery.
- Request confirmation of successful delivery and return an error message if not received.
Upon completion, we will have the perfect backend for processing contact forms. Alternatively, our server will also provide a solid base to build a full-stack MERN app with plenty of functionality.
The production version of the server we are building today powers the backend of Ormica, a real estate investment firm in S. Florida.
- A basic understanding of fundamental programming concepts and familiarity with at least one server-side programming language such as [Node, Python, Ruby, PHP].
- A code editor such as Visual Studio
- Node.js and npm locally installed. (Current LTS version preferred)
Some developers, including myself, prefer to use nvm or nvm-windows to simplify Node version management, which is perfectly fine. For further reference you can also check out How To Use Multiple Node Versions With NVM On MacOS - Node Version Manager
Part 1: Dependencies
The moment has arrived! Time to write some code.
Begin with these terminal commands to make an empty directory wherever you wish to store your server's local version and create the first file using npm.
Follow the terminal prompts from npm to create a package.json file. In most cases, the default values will suffice, but be sure to change the entry point to server.js instead of the proposed index.js.
Now we need to add the required dependencies (npm packages) to our project. Run the following command and notice that npm automatically creates a new directory called node_modules. This is normal, so don't change or configure anything in this folder.
Let's glance at a brief overview of each package.
- Express is a minimal and flexible Node.js web application framework that provides a robust set of features.
- Nodemailer is a module designed to allow Node.js applications to send emails securely and efficiently.
- Morgan is named after Dexter (a show you should not watch until completion) and provides HTTP request logger middleware for Node.js.
- dotenv is a zero-dependency module that loads environment variables from a .env file into process.env.
Part 2: Routes
Let's begin by creating a routes folder containing routes.js.
Open routes.js in your code editor and establish a baseline by requiring the dependencies at the top of the file.
As you can see, Express has its own built-in router. I have opted to use this option instead of a separate npm package. This helps keep our application lightweight and efficient.
Our next order of work will involve setting up authentication using our Gmail account credentials. Don't forget to add the .env file in the root directory rather than our current location.
Remember the transport function we mentioned earlier? In this step, we will construct that same function. Let's have a look!
Now let's build the API routes. We will simultaneously define the schema for our JSON object (email).
In simple terms, we are telling Nodemailer about the form data it will be receiving from the front-end and how it should translate said data into a structured email.
Finally, we call the transporter.sendMail function, Nodemailer works its magic, and the email goes on its merry way to the recipient's inbox.
The last block of code in this file instructs Express to use the routes we have established; finally, we export the entire router to the Node server.
NOTE: If you are unfamiliar with process.env or merely need a > refresher, this Codeburst article provides a splendid reference point.
Part 3: Server
Let's create a server.js file in the root directory and open it with the editor.
Here we are just ensuring everything runs smoothly. I could write an entire article about each of the parameters defined here, but the template is pretty standard.
Let's start by defining some initial requirements.
Now we should check the environment to see if we are running in production. If so, we use a cluster of Node processes to distribute the stress of running the application as evenly as possible across the server cores.
We will then connect to the frontend, priority serve our static HTML files, define some middleware for AJAX parsing, and finally call the routes we are importing from the routes.js file, all in that order.
We wrap it up with some error logging for the development environment, and voila! Our Express mail server is humming along.
SMTP Email Server is complete! Congratulations!
NOTE: If you encounter difficulty with the authentication
process, read this Google Support documentation! It will save
you hours of debugging and Excedrin.
We’ve successfully created an SMTP Email Server using Express and Node. We also learned how to integrate Nodemailer and Gmail to streamline the mailing process.
Feel free to clone the source code and explore your own methods of implementation. I hope you have found this tutorial useful, and thank you for taking the time to follow along!