Currently I am able to send E-Mails to groups like confluence-users or to users that have contributed recently.
I'd like to have the ability to send an E-Mail to all users that are space administrator of at least one space.

In our environment every user is allowed to create new spaces. We had already use-cases that required me to send E-Mails to all space admins (e.g. "Please add an Imprint to your space", or "Please use space-categories"). In order to contact them, I had to look up all space admins manually and to send an E-Mail from Outlook. It would be nice, if I was able to contact them in an easy way.