Custom Field in Email confirmation

I created a new field “billing_degree” in “Billing Fields” (to use in between “Dear Mr. Dr. Prename Lastname” salutation in the email confirmation), checked “Display in Order Detail Pages” and “Display in Emails”.

The field is shown in the checkout billing fields but in the order confirmation Email it is placed at the bottom of the email above the billing address, which makes no sense at all. How can I get this field into the salutation placeholders at the beginning of the confirmation email?