How to block emails for specific customer?

You can prevent the sending of emails to specific customers by adding their email IDs to the block email list. Any email addresses added here will not receive automatic emails, even if the customer makes a purchase from your store.

Step 1: For that, Navigate to Notifications  >> Email

Step 2: Select the Block/UnBlock tab, enter the email address for which you wish to disable email sending, and then click on the save button.