[exim] making my HELO = my RDNS

Is there a simple way to set my HELO to be the same as my RDNS?

Godaddy has implemented a new rule where if the RDNS of the helow
doesn't match the IP of the interface then they bounce the message. So I
need to figure out how to make the HELO change based on the transport so
the HELo matches the IP of the interface that it is being sent from.