How can I change where Recurly invoices are sent?

Recurly billed invoices by default are sent to the Billing Contact email address listed under the Site Settings Configuration page. You'll want to simply visit the Site Settings page under the Configuration tab on the left-hand navigation menu, scroll down to the contact details and change the Bill Contact field. Please note that this email is also used as the default "FROM" address for all customer facing emails as well, however this can be changed on a per template basis from within the Email Templates Configuration page.