I have a published newsletter and I want to embed it in a page. I tried to copy the html code, but for a reason it appeared with a weird format.
So, I suppose that I need a short code to add in my page, that will call the old newsletter.
A newsletter is a full HTML page, if you copy it in a WP page the theme tries to apply its own style, this is way it cannot be published in this way. Try the archive extension, it could help.