A web site, you login with google oauth, and after that send invitations to all of your contacts. Including that email accounts that are reserved for monitoring and alert systems. See how my college receive and sms from and alert system and asking to ack the alert "you have and invitation from reference.me" was fun, but not serious.

So for your good. Don't even enter this spammers site.

And if you do, remember to revoke access from your oauth provider.