How can I prevent profiles from Amazon from being sent emails?
For flows, you can add a flow filter that will exclude any customers with an Amazon email domain. Once you're inside a flow, click Edit Definition. Add a flow filter with the following criteria: Properties about Someone > Email doesn't contain @marketplace.amazon.com.
If you plan to send a campaign, you can create a segment based on the audience you're targeting, and then add the same definition in that segment as displayed above.
For more information, check out our article on Integrate with Amazon Marketplace.