Sympa is an open source mailing-list server, which can be used for discussion or diffusion. Also it means "nice" in French.
This is what some of my clients use as a newsletter service. And yes, it's nice. If you can send an email, you can send a newsletter to thousands of people, basically.

The package wagtail_newsletter was published right when they asked me to allow them to write their newsletters directly from Wagtail.

First I had to write a new "backend" to use Sympa instead of MailChimp. Each tool has a very different "philosophy" so it was an interesting process.

Then I took some time to think about the content: what do we want to write in a newsletter? How does it fit with the rest? (That is, where do I put my new Page model? Do I even need one?)

And finally I worked on the presentation of content: I had to work with mjml for the first time and think about text alternatives. Wagtail was very helpful on that particular aspect.

At the end of this talk you will know what to expect with wagtail_newsletter and you will love Wagtail even more.