@Tshoxoma Welcome to the Monday Community!
The ability for Mirror columns to be used in Automations have only recently been added, but its still a limited feature.
There is a simple workaround that I currently use for multiple automations identical to yours! You will need to install the app General Caster from the App Marketplace. It works similar to the formula column except it process outside of Monday and send the results to basic columns. So in this case, you will have the Integration send the email from your Mirror column to a text column of your choice and then you can use the Text column in your automation!
Hope that helps. If you need more info or help to set this up, just let me know!