It is possible to prevent visitors from subscribing with a disposable email (a fake email that will be used only once). We will use the Wisepops JS callbacks feature to download a list of disposable email providers, and ensure that the listed domains are not used in the email field.

Step 1: 

From our editor, create a new JS callback listening for the event Before popup display:

Step 2:

Copy/paste the following snippet as the script of the created callback:

// Get list of disposable email domains
var xhr = new XMLHttpRequest();'GET', '', true);
xhr.responseType = 'json';
xhr.onload = function () {
  if (xhr.status === 200) {
    window.wisepopsDisposableEmailDomains = xhr.response;

When the popup is being displayed, we will load the list of disposable email providers from the open source project ivolo/disposable-email-domains.

This fetched list is loaded asynchronously - meaning that it won't delay the display of the popup.

Step 3:

Create a second callback listening for the Before form submit event.

Step 4:

Copy/paste the following snippet into the callback's script:

// Prevent sign-up with a disposable email
// This script uses the list fetched by the before-popup-display callback
var isDisposableEmail = false;
var emailField =['email'];
var emailParts = emailField.value.split('@');
if (emailParts.length === 2 && window.wisepopsDisposableEmailDomains) {
  isDisposableEmail = window.wisepopsDisposableEmailDomains.indexOf(emailParts[1]) > -1;
if (emailField) {
  if (isDisposableEmail) {
    emailField.setCustomValidity('This domain is not allowed');
  } else {

Here we will try to match the filled email domain against the previously fetched lists. If a match is found, we will display this error message: "This domain is not allowed.” 

You can learn more about how to write custom validations for your forms here.

You're done! You final config should look like this:

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