'invisible' new users' registration

good day everybody out there. i set up WP multi-site successfully on my single WP install some hours ago. when i checked my email right now, i got a meesage titled “new user registration” and the body of the message reads:
“New User: kraljzbnx
Remote IP: 37.59.151.190.”
but when i check on my site for users, their name are not listed ( in fact there are there such registrations). can someone put me through on what could be happening. are these spammers? and how do i handle spammers if that be the case. thank you, very much.