I've used other email validation tools, but this is the one one that has its own plugin to validate email from users as the sign-up to your site, this is a great way to keep bots/hackers at bay, and also to ensure your users are using emails that you and send transactional emails to (or marketing, depending on your use case).

Absolutely loving this!

Only issue is that it repeats three validations on each signup, so it's consuming 3x times the credits, hopefully it's a glitch from the beta (plugin) that will get sorted out quickly in the next version of the plugin.