There are two ways to unsubscribe from a project's updates:
1. At the bottom of every email, there’s an “Unsubscribe” button which you can click to unsubscribe from that project’s updates.
2. You can also go to the main page for any Mirror project to which you've subscribed, or any of their entries, click the “Subscribed” button anywhere it appears, and you will be unsubscribed.