shawfactor

mattsenate

This plugin is can be used for petitions, events, or any verified list and as far as I know is unique in WordPress.
Creating a petition/list/signup is as easy as adding a shortcode to a post or page (or CPT). From there additional editors are available to configure easch aspect of the sign up. Everything is completely self hosted and all list members become users of your site (not a third parties).
Available shortcodes:
[lh_signing_form] (enable signatories on any post, page, or custom post type)
Unconfirmed signatories: [lh_signing_unconfirmed_count]
Confirmed signatories: [lh_signing_confirmed_count]
Total signatories: [lh_signing_total_count]
[lh_signing_unconfirmed_list] (unformated list)
[lh_signing_confirmed_list] (unformated list)
You can customise the display of the signing form ([lh_signing_form]) via a number of shortcode arguments more information is available <a href="https://lhero.org/portfolio/lh-signing/" title="Additional Plugin documentation" rel="nofollow ugc">here</a>

LH Signing

LH Signing allows you to create configurable validated lists like petitions or event sign ups. It is the only self hosted solution in WP

b4ecommerce

A lightweight plugin that checks for the most common email typos in the customer’s email and provides them with a warning. Using this plugin your customers will be much more likely to enter a valid email address, which will simplify and improve your order management.
USAGE 
You don’t need to configure the plugin, just upload and activate it and it’s ready to go.
CURRENTLY CHECKING FOR THE FOLLOWING EMAIL DOMAINS
<ul>
<li>Gmail</li>
<li>Hotmail</li>
<li>Outlook</li>
<li>Protonmail</li>
<li>Yahoo</li>
</ul>

Checkout email validation for WooCommerce

A lightweight plugin that checks for the most common email typos in the customer's email and provides them with a warning.

LH Signing vs Checkout email validation for WooCommerce