Again, my recollections are decades old, but the rules on franking of mass mailings limited things like the numbers of pictures of the congresscritter that could be included, the amount of self-referencing in text, and a bar against overtly political messaging. The idea is that congressional "newsletters" are supposed to be non-partisan and informational in character, as opposed to political. The lines can get awfully blurry.
But if democrats now regard "Obamacare" as a term of invective, that is good news.