Is this the same with sharing photos from G+?

I have a circle for family and some of them have G+ and some don't. When I share a photo with the circle some of them get the emails OK (non G+ users?), some get the emails but are asked for a pasword and user name and some don't even get the emails?

I even added Guy Kawasaki to a circle and shared a pic but he never got my invite and reported it weird

Thanks for any help

Mike