Sending to all Administrators of sub-sites, not subscribers?

I was advised to use the mass email plugin to send out messages to all my users. However that also sends to subscribers which I do not want to do. I only want to send to all administrators/site owners.

So I saw a thread that said you could do that using the e-newsletter plugin and I see the option to send only to administrators but it looks like it is not sending to all administrators of all my sub sites, only the administrator of the site where I am creating the newsletter.

How can I send to a message to all users with the role='administrator', is that possible?

I go the members section and it does not show the members for all my sub sites so I assume they will not get the message.