Someone (named John Smith) checkout in my store many times with wrong contact message, such as wrong or fake email, address, phone. This situation will affect my shop data analysis. I used to use some APP about block IP or customer's email, but didn't work.
malicious checkouts occur many times everyday. I feel very annoyed. Who can help me about it？
First off you should definitely call shopify so they can blacklist this ip and make sure it's not something on their end that is allowing this.
Secondly, you can use a honeypot method by changing a few lines of code and making your checkout button an image. This would be a temporary solution, until shopify can better prevent this. Basically hide a button on the cart page with a checkout link and an alt tag that says checkout - hide it so customers don't see it and on the actual "Checkout" button, you can make an image link and remove the alt and title tags from the actual checkout button.
Customers wouldn't know the difference, but it looks like a bot is doing this, and if it is, then that would solve it and the bot would end up just leaving the site.