Aaron D. Campbell

This plugins gives you a great framework to use for integrating with MailChimp.
Requires PHP5.

MailChimp Framework

MailChimp integration framework and admin interface as well as WebHook listener.  Requires PHP5.

Saint Systems

Adam Anderly

WP WooCommerce Mailchimp provides simple and flexible Mailchimp integration for WooCommerce.
Automatically subscribe customers to a designated Mailchimp list and, optionally, Mailchimp interest groups and tags upon order creation or order completion. 
This can be done quietly or based on the user’s consent with several opt-in settings that support international opt-in laws.
Upgrade to <a href="https://www.saintsystems.com/products/woocommerce-mailchimp-pro/" rel="nofollow ugc">WP WooCommerce Mailchimp Pro</a> for more advanced features including WooCommerce Subscriptions support and the ability to set product-specific lists, groups and tags.
<h4>Features</h4>
WooCommerce Event Selection
<ul>
<li>Subscribe customers to Mailchimp after order creation</li>
<li>Subscribe customers to Mailchimp after order processing</li>
<li>Subscribe customers to Mailchimp after order completion</li>
</ul>
Works with Mailchimp Interest Groups and Tags
<ul>
<li>Set one or more interest groups to add users to based on the selected Mailchimp list.</li>
<li>Set one or more tags to add users to based on the selected Mailchimp list.</li>
</ul>
Opt-In Settings
<ul>
<li>MailChimp double opt-in support (control whether a double opt-in email is sent to the customer)</li>
<li>Optionally, display an opt-in checkbox on the checkout page (this is required in some countries)</li>
<li>Control the label displayed next to the opt-in checkbox</li>
<li>Control whether or not the opt-in checkbox is checked or unchecked by default</li>
<li>Control the placement of the opt-in checkbox on the checkout page</li>
</ul>
<h4>Translation Support</h4>
Would you like to help translate the plugin into more languages? Join our Translations Community at https://translate.wordpress.org/projects/wp-plugins/woocommerce-mailchimp.
WooCommerce Mailchimp translation is managed through WordPress language packs here: https://translate.wordpress.org. This allows WooCommerce Mailchimp to be translated into other languages. The preferred tool for translating plugins is called <a href="https://make.wordpress.org/polyglots/handbook/tools/glotpress-translate-wordpress-org/" rel="nofollow ugc">GlotPress</a>. You can <a href="https://make.wordpress.org/polyglots/handbook/tools/glotpress-translate-wordpress-org/" rel="nofollow ugc">read about how GlotPress works in the WordPress Translator’s Handbook</a>.
Thanks in advance for your help on any translation efforts!
We also support bundled translations via:
<ul>
<li>Included woocommerce-mailchimp.pot file</li>
<li>WPML support via wpml-config.xml</li>
</ul>
Included Translations:
<ul>
<li>English (US) (default)</li>
<li>French.</li>
</ul>
Custom Translations
If you don’t want to use WordPress language packs or bundled translations, you can use your own custom translations.
<ul>
<li>Place custom translations in <code>/wp-content/languages/woocommerce-mailchimp/woocommerce-mailchimp_{lang}_{country}.mo</code>. This ensures they won’t get overwritten by plugin updates.</li>
</ul>
Translation Loading
If no custom translations are present, languages will be loaded in the following order:
<ul>
<li>From WordPress language packs in: <code>/wp-content/languages/plugins/woocommerce-mailchimp/woocommerce-mailchimp_{lang}_{country}.mo</code></li>
<li>From the plugin bundled in: <code>/wp-content/plugins/woocommerce-mailchimp/languages/woocommerce-mailchimp_{lang}_{country}.mo</code></li>
</ul>
<h4>Multisite</h4>
<ul>
<li>All features should work for each blog in multisite installations.</li>
</ul>
<h4>Requirements</h4>
WP WooCommerce Mailchimp requires PHP 5.6+ (PHP 7.0+ recommended). You’ll also need to be running WordPress 4.7.0+ and have WooCommerce 3.5.0+.
<h4>Documentation & Support</h4>
Online documentation and code samples are available via our <a href="https://support.saintsystems.com/hc/en-us/sections/201959566" rel="nofollow ugc">Help Center</a>.
Please visit the 
<a href="https://wordpress.org/support/plugin/woocommerce-mailchimp" rel="ugc">WP WooCommerce MailChimp support forum on WordPress.org</a> for basic support and help from other users. Since this is a free plugin, we respond to these as we have time.
Dedicated support will is available for <a href="https://www.saintsystems.com/products/woocommerce-mailchimp-pro/" rel="nofollow ugc">WP WooCommerce MailChimp Pro</a> customers.
<h4>Contribute</h4>
All development for WP WooCommerce MailChimp is <a href="https://github.com/anderly/woocommerce-mailchimp" rel="nofollow ugc">handled via GitHub</a>. Opening new issues and submitting pull requests are welcome.
<a href="https://trello.com/b/VWBdLVuI/woocommerce-mailchimp-development" rel="nofollow ugc">Our public roadmap is available on Trello</a>. We’d love it if you vote and comment on your favorite ideas.
You can also keep up to date with <a href="https://www.saintsystems.com/products/woocommerce-mailchimp-pro/" rel="nofollow ugc">WooCommerce MailChimp Pro</a> development by <a href="http://eepurl.com/bxcewL" rel="nofollow ugc">subscribing to our newsletter</a>.
Also, if you enjoy using the software <a href="https://wordpress.org/support/plugin/woocommerce-mailchimp/reviews/?rate=5#new-post" rel="ugc">we’d love it if you could give us a review</a>!

WP WooCommerce Mailchimp

Simple and flexible Mailchimp integration for WooCommerce.

MailChimp Framework vs WP WooCommerce Mailchimp