I'm not sure anyone should use PDF's for material designed to be read online. But this goes double if it's a newsletter of some kind that is not to be published off-line.
If you are going to use PDF for this purpose, PLEASE give your readers a break and don't use some kind of two or three column format designed for print that calls for scrolling up and down. I've raised this issue with my otherwise wonderful alma mater, who publishes a nice business journal that is generally worth reading. Surely they can afford two formats, one for online reading, and one for print?
I think this has damaged their brand image, and I'm not kidding around here. How can you claim to be leading edge thinkers when you can't get this kind of thing right? They could take tips from the journal of a major consultancy, that offers both.