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.

Vishal Kothari

This plugin validates the existence of the domain name that is entered in the email address while checkout. This plugin strengthens your email validation by more than just the regular expression matching, thereby reducing chances of loosing an order due to incorrect email address & increasing accuracy of your data.
The checkout process cannot be completed till the email address is entered with the correct domain, thus eliminating any chances of a wrong email address (at least the domain can’t be wrong).
If the domain is not a valid domain, it will show an error and not allow the customer to checkout till the email address is entered with the correct domain.
Other free plugins for WP e-Commerce:
<ul>
<li><a href="https://wordpress.org/extend/plugins/viral-coupon-for-wp-e-commerce-lite" title="Viral Coupon Plugin" rel="ugc">Viral Coupon Lite for WP e-Commerce</a> – Social Media Promotion Tool for your store (Facebook)</li>
<li><a href="https://wordpress.org/extend/plugins/order-delivery-date" title="Order Delivery Date" rel="ugc">Order Delivery Date</a> – Allow customers to choose their order’s delivery date</li>
</ul>
Premium plugins for WP e-Commerce:
<ul>
<li><a href="http://codecanyon.net/item/viral-coupon-for-wp-ecommerce/2644621" title="Viral Coupon Pro" rel="nofollow ugc">Viral Coupon Pro</a> – Promotes your store on Twitter & Google+ in addition to Facebook.</li>
</ul>

Email Domain Checker for WP e-Commerce

This plugin validates the existence of the domain name that is entered in the email address while checkout for WP e-Commerce store owners.

Checkout email validation for WooCommerce vs Email Domain Checker for WP e-Commerce