I assume this has to do with approval of congressional newsletters. Newsletters are bulk mail and have long been distinguished from individual constituent mail.
With modern word processing, this gets a bit tricky. It has been many years since I worked on the Hill, but offices used to be (and I presume still are) required to submit newsletter copy for approval by (IIRC) the House Administration Committee, or whatever it is called these days. Again if recollection serves, back in my day small lists could be mailed without prior review, but anything over 500 pieces had to be submitted.
Newsletters are not supposed to be political in nature, so very murky lines get drawn about what is permissible. This leads to periodic dustups.
If the dems are censoring Obamacare, they are opening themselves to mockery. Assuming, of course, that tone deaf Republicans are agile enough to respond.
thanku...if house were the senate and roles were reversed...they would change the rules