zhanming

<a href="https://litesub.com" rel="nofollow ugc">Litesub</a> is a simple service that helps professionals and small businesses build subscription popups and publish newsletters. With this plugin, you can create and add a popup to your site in minutes, with least effort and no coding. Then you can create newsletters in the same way you write posts or building pages. Litesub will deliver them for you, handle the unsubscriptions, and track the opens.
In your newsletter, you can choose the posts you want to send to the subscribers. They will be listed in the newsletter and presented in your site’s theme. Now you can easily build elegant newsletters like those big companies do.
At this moment, Litesub delivers newsletters with Gmail API, so you will need a Gmail/Gsuite account. More delivery methods like SMTP, Mailchimp, will be added soon.
Litesub is free if you have less than 2000 subscribers, and depending on your Gmail account type, can send at most 500 or 2000 mails for you per day.
<h3>Minimum Requirements</h3>
<ul>
<li>PHP version 5.2.4 or greater (PHP 5.6 or greater is recommended)</li>
<li>MySQL version 5.0 or greater (MySQL 5.6 or greater is recommended)</li>
</ul>

Litesub

Litesub helps you to add subscription popups and send newsletters in WordPress.

ethanpil

A WordPress plugin that allows visitors to subscribe to Dreamhost announce lists via a widget, as well as view and manage the lists in the WordPress admin panel. Additionally the WP Admin can send HTML emails to the lists using the current 
Wordpress template.
Think of it as a poor man’s version of the Constant Contact service! All due to the Dreamhost API.

WP-DreamLists

Subscribe to Dreamhost announce lists via widget, view & manage lists in the admin and send HTML emails to the list. A poor mans Constant Contact!

Litesub vs WP-DreamLists