Targeting with Blogs

The key thing to understand for public versus private groups, is whether messages in the group in question should be seen by people who are not members. If it’s a group for management, the answer is likely no. If the group is more casual or open in nature, public is best.

Public is recommended for most groups simply because you should not target a private community and a public community (this makes the post public). If you have a large amount of private communities, you could wind up having to create many instances of the same message, which will make it more difficult to manage.

Private communities should never grow to more thank 5k users as this is not scalable per SharePoint software boundaries.