Send email/Slack alert when more than 2 customer emails use the same shipping address

[kel_dee]

Hi all, 

We've had a few people taking advantage of our points program, by creating 100s of emails and gaining new subscriber points.  They are able to get tons of free products this way. The only way we were able to catch these individuals is by their shipping address which is the same for all their bogus customer accounts.

I now have Flow set up to cancel orders being shipped to these addresses. However, I've recently noticed the same person is back at it with a different shipping address this time. 

Is there a way I can prevent people from doing this?  Ideally, I'd make a rule where if 2 or more customers use the same shipping address ---> send us an alert/email. Doesn't seem like this can be accomplished in Flow, since flow wants specific values. 

Any ideas?

Thanks!