thebluecube

This plugin adds some additional features to the Gravity Forms plugin:
<ul>
<li>Input ID change (if the form has not received any entries yet)</li>
<li>Advanced input validations</li>
<li>Form access control</li>
<li>Advanced conditional logic shortcode to be used in email notifications</li>
</ul>
Documentation: https://thebluecube.com/wordpress-plugins/bluecube-mighty-gravity-forms/documentation/

Blue Cube Mighty Gravity Forms

This plugin adds some additional features to the Gravity Forms plugin:

Ikbear

BillionVerify Email Validator checks email addresses in real time as your forms are submitted, stopping fake, mistyped, disposable and undeliverable emails before they reach your database. Cleaner signups mean fewer bounces, less spam and healthier email campaigns.
The plugin verifies each address against the BillionVerify API — performing syntax, MX and SMTP mailbox checks — and rejects the submission when the address matches a status you have chosen to block.
Key features
<ul>
<li>Real-time verification during form submission (no front-end changes required).</li>
<li>Detects valid, invalid, disposable, catch-all, role and risky addresses.</li>
<li>Choose exactly which statuses block a submission — invalid only by default.</li>
<li>Custom error message shown to visitors.</li>
<li>Built-in connection test and single-email test tool in the admin.</li>
<li>Result caching to save credits on repeated addresses.</li>
<li>Fail-open by default: if the API is unreachable or credits run out, forms keep working.</li>
</ul>
Supported forms
<ul>
<li>Default WordPress registration form (including multisite signup)</li>
<li>WordPress comment form</li>
<li>WordPress lost-password form</li>
<li>WooCommerce checkout and account registration</li>
<li>Contact Form 7</li>
<li>WPForms</li>
<li>Gravity Forms</li>
<li>Elementor Pro Forms</li>
<li>Fluent Forms</li>
</ul>
<h3>Third-Party Service Usage</h3>
This plugin sends email addresses to the BillionVerify API (https://billionverify.com/) for verification. Through API calls to BillionVerify servers it verifies email addresses and retrieves account credit information, using the following endpoints:
<ul>
<li>Verify an email address: https://api.billionverify.com/v1/verify/single</li>
<li>Retrieve credit balance: https://api.billionverify.com/v1/credits</li>
</ul>
By installing and activating this plugin, you consent to the transmission of submitted email addresses to these URLs for the purpose of verification. Use of the BillionVerify service is subject to BillionVerify’s Terms of Service (https://billionverify.com/terms) and Privacy Policy (https://billionverify.com/privacy).

BillionVerify Email Validator

Real-time email verification for your WordPress forms. Block invalid, disposable, catch-all and role addresses using the BillionVerify API.

Blue Cube Mighty Gravity Forms vs BillionVerify Email Validator