ethanpil

Install this plugin into any WordPress system with a working Gravity Forms plugin and all known disposable email address hosts will be rejected and fail validation. This only checks the field type “email” and does not require any configuration or special settings. Its global, if its turned on, then its working.
Thanks to adamloving for the initial list: https://gist.github.com/adamloving/4401361
This WordPress plugin is brought to you by <a href="https://www.angeleswebdesign.com" title="Los Angeles Web Design WordPress Experts" rel="nofollow ugc">Los Angeles Web Design</a>

Gravity Forms Reject Disposable Emails

Reject disposable email addresses in Gravity Forms email fields.

IsTempMail

This plugin will verify every email address submitted by users. 
It’ll automatically detect and block disposable, temporary email addresses. 
It’ll give a nice warning message when users are signing up, logging in, 
or changing email to a temporary email.
The plugin checks the domain name using a service named 
<a href="https://www.istempmail.com/?ref=wp" rel="nofollow ugc">IsTempMail</a>. 
If a domain name is blocked, it will be stored into a local blacklist. 
You can also manage your own local whitelist and blacklist to allow or 
disallow certain domains.
The plugin integrates with the WordPress built-in function <code>is_email()</code>. 
It works seamlessly with other plugins including WooCommerce, 
Contact Form 7, Gravity Form, Jetpack/Grunion contact forms, Kadence Blocks Forms as well as 
other formbuilders and ecommerce plugins and WordPress’ own registration form.

Block Temporary Email

This plugin stops users from giving you disposable or fake email addresses when signing up. This helps reduce spam and fraud.

Gravity Forms Reject Disposable Emails vs Block Temporary Email