You could create a group "all" which is private - hidden - no tags.
Every user is member of this group. So you cloud mention the group @all where all users are members.
I set Admin Approval in Registration option in my website, and sometimes I see spam users register and I click on Red Cross button in Registration Queue.
Now I wanted to see all of them, but I see only the ones I approved manually. I did not see any options to see them.
I also searched one of them, but it found nothing.
Would you help me how may I see them?
Thanks in advance
You can't. User accounts aren't created until approved.
So you mean another user can register with one of those users again? Am I right?
That's right, the username/email can be used by another person if you reject someone.