In my group, we had an internal newsletter for several months and only posted it on the main wall. The main drawback was that we did not reach our inactive people or people having disabled e-mail notifications as one of our goals was to activate the more inactive ones. Unfortunately, we stopped it due to a lack of resources, mainly time.
For our general assemblies, we as an association are legally forced to invite everybody via letter or e-mail. Therefore, we ask new people to sign up through a form on our website before we let them in on Karrot.