Elias here with Shopify Support. That is a great question!
I understand you’re looking for a way to bulk import a list of emails so Flow can notify you when an email from this list tries to complete a transaction on your store. I’m afraid there isn’t a way to bulk upload a list for Flow. Nonetheless, I’d be happy to share this feedback as a feature request with our developers.
Instead of using Flow for notifications of these transactions, I would recommend using Fraud Filter. Although Fraud Filter, like Flow, isn’t able to import a bulk list; however, Fraud Filter is able to flag these orders and notify you via email. Fraud Filter also has a function to automatically cancel the order, which may help reduce your workload. Fraud Filter can also prevent specific IPs from checking out on your website. If you’re interested, we have a guide to help you with setting up Fraud Filter as well.
That said, if you’d like to block certain individuals from visiting your store, there are third-party apps that can block their IP from accessing your website completely. I’ve handpicked a couple for you to look into:
If you need any assistance with these apps, you can always reach out to the developers directly through the contact information found in the Support section of the app’s page.
I hope this provides a couple of solutions for you to explore. If you have any further questions regarding this topic, feel free to reply to this thread and I’d be happy to help.