Some methods I’ve recommended:
- Simplify the newsletter output so it can easily be parsed in Discourse; this is fairly easy to do, but reduces the benefits of using a newsletter system
- Use Discourse to create the content, send a newsletter to highlight links to the community site
- Create a topic for discussion, and link to the hosted newsletter elsewhere
Most of the time folks are asking for sending and sharing their own newsletter. It sounds like you might want to re-share newsletters sent to you, in which case there is a gotcha: newsletters are almost always customized to included individualized subscription links in the message, and sharing those means others can use them to change the subscription status.