What is the best solution for securing from all saving and copying techniques in the publishing industry without damaging the reader experience (exemple an e-newsletter)?
There isnt one. In general, DRM (digital rights management) interferes far more with the experience of honest people than with criminals. Theres not much a professional hacker couldnt crack and redistribute; the Home Shoplifting Network on Usenet is proof of that.
You can use secured PDFs to prevent people from printing, editing, and copying, and then only a really determined person will take a screen shot, scan it in, run it through Optical Character Recognition, and go merrily ahead and do all the things you were trying to prevent. PDF security is at least fairly unobtrusive, and its generally a good idea to use, but the best it can do is make copying the file more troublesome.
But the only things that would come close to providing you with unbreakable security would make it so difficult to access the information that people probably wont bother trying, or theyll spend more time complaining about the DRM than taking whatever action you wanted them to take as a result of reading your newsletter.
The best thing is probably to establish your brand and style in such a way that people will automatically recognize the content as yours if someone tries to pass off a copy. (And there are ways to track where your articles show up; for help see Plagiarism Today.)