In this post I will show you how to redirect all OWA requests to the correct HTTPS address. It works not only with OWA, but with EWS and/or ECP.
I’ve been doing this for as long as I can remember in Exchange 2007/2010/2013 so that requests go automatically to https://owa.customer.com/owa (or /exchange). So, if someone goes to http://owa.customer.com or https://owa.customer.com, they get redirected to the correct (secure) URL.