shawfactor

This plugin allows you to send html formatted email message directly from your WordPress dashboard. These emails are based on the posts you create within WordPress. Optionally you can add content at the top and bottom.
These emails are formatted based on a template you can modify both by adding widgets and by editing the template in your theme or child theme.

LH Email

LH Email enables you send html emails based on your posts, directly from your WordPress dashboard.

EverPress

Xaver

Mailster Newsletter Plugin

Integrates Mailster Newsletter Plugin with Gravity Forms to subscribe users with a Gravity Form. 
Requires the Mailster Newsletter plugin and the Gravity Forms plugin
<blockquote>
This Plugin requires <a href="https://mailster.co/?utm_campaign=wporg&utm_source=wordpress.org&utm_medium=readme&utm_term=Gravity+Forms" rel="nofollow ugc">Mailster Newsletter Plugin for WordPress</a>
</blockquote>

Mailster Gravity Forms

Integrates Mailster Newsletter Plugin with Gravity Forms to subscribe users with a Gravity Form.

LH Email vs Mailster Gravity Forms