A programming language called JavaScript is utilized for both front-end and back-end development. This post will offer a shift in viewpoint from the server-side to the client-side by utilizing JS to send emails from an application with no back-end.

JavaScript email transmission

JavaScript code cannot send emails by itself since server sockets are not supported. A server-side language that communicates with the SMTP server is needed for this. For the server script to send emails from the browser in response to queries, JavaScript is also used.

Why you would want to use JS to send emails

Emails are often sent through the server-side of a standard app. A server setup utilizing back-end technology is required. The server side receives a request from the client-side and responds by creating an email and sending it to the SMTP server. Why then use JavaScript to send emails directly from the client side. Such a method is quite helpful for developing contact forms and other user interfaces for web apps since it enables email sending without requiring the user to reload the page they are currently viewing. Additionally, you don't need to play around with server programming. If your web application solely sends emails in response to contact forms, this is a compelling argument. You can choose from a few options below to enable client-side email sending in your app.

Mailto: for delivering form data,

You can program the browser to launch the default mail client to send an email directly through JS. Although it is not technically possible to send an email straight from a browser, the mailto: method can be used.

HTML example

See how the following piece of code functions:

You'll see the following when you open it in the browser:

Following the data submission, the browser launches the default mail client.

Although the mailto: method is a fairly simple implementation, it has the following specific drawbacks:

  • Given that the data is supplied in the form that the browser sends, you do not influence how the data is laid out.

  • Mailto: doesn't guard against spambots gathering your email address. A link might be built-in JS in the past to help with this. Nowadays, a growing number of bots use JS and do not solely rely on HTML produced by the server.

MailSlurp true email sending

A free package called SmtpJS can be used to send emails from JavaScript. To complete the task, an SMTP server and a few adjustments are required. Since mailslurp is a practical email testing solution, it serves as the server in this example. The procedure to follow is outlined below: Create an HTML file with the following script in it (for instance, test.html):

A button that will activate the JavaScript function should be created.

Create the JS function to use SmtpJS.com to send emails.

You can include an array of email addresses in the To: attribute if you have numerous recipients. Send emails by running “test.html” in the browser.

The problem with the code example above is that the client-side script makes your login and password visible. If you use the SmtpJS encryption option, you can resolve this. After completing the necessary fields, click the box that says "Encrypt your SMTP credentials." Following that, select Generate security token, and use it in your JS function in place of the following SMTP server settings:

An HTML email sample and an email with an attachment are shown below. This is how the email will appear in the recipient's inbox, thanks to mailslurp's GUI.

An example of HTML email coding:

Sample of the code needed to send an email with attachments Use the Attachments property to send an email with an attachment as shown:

Sending without code

Without using any server code, mailslurp.com enables connecting email providers, creating email templates, and sending them from JavaScript. Choose a service to connect with and create an account. Both personal services like Gmail or Outlook and well-known transactional service choices like Amazon SES or Mailgun are offered. mailslurp is used in this illustration.

The built-in editor can be used to create email templates. There are many possibilities for creating material in the editor, along with additional helpful tools like auto-reply, reCAPTCHA verification, and others. Additionally, you must be familiar with the fundamentals of writing your HTML email template. Click Save after you're done. The fact that the standard email characteristics are concealed is one of mailslurp.com's key advantages. Since the recipient field is included in the template and cannot be changed using JS, you transmit the template that was previously set up. You must now install the mailslurp SDK. Npm can be used for this:

Via browser

You should insert the following code before the closing tag if you need to use mailslurp on your website:

Two techniques can be used to send the email itself:

  • mailslurp.send
  • mailslurp.sendForm.


Let's send an email directly from the browser to see if mailslurp.com functions as expected. We have created a straightforward template and set up the mailslurp email service. Now, we must write the following code into an HTML file:

Try it out in your browser by opening the mailslurp Demo Inbox. It works!

However, there is a way to send emails without ever using a browser that is simpler and faster. After testing them, “mailslurp Email Delivery” enables you to rapidly authenticate your domain and send emails using SMTP or API.

To conclude

You can avoid dealing with server-side coding even if sending emails is a server-side function. Two practical options for streamlining your front-end and enabling email sending are:

  • MailSlurp

MailSlurp is superior since it conceals common email properties and lets you send any templates you've previously set up. While the mailto: approach is different, it too has its uses.