With version 6.1.1 The Newsletter Plugin adds the ability to add custom composer blocks by third party plugins and themes (or even without coding a theme or a plugin).
We hope this new feature will give everyone the opportunity to create new stunning and profitable newsletters, using even better the blog contents or business services.
Of course we wrote up a started documentation on custom blocks. See yourself how much easy is to add a new composer block. And if you have any trouble with this new feature or our documentation let us know!