Need to change the external IP address of exch 2013 server
We have 3 ip external addresses that our exchange 2013 server can use but only 2 of them were listed with our external spam filter. Our exchange server rebooted today and now the external ip address is one of the 3 that is was not listed with the external spam filter. They said it could take up to 4 hours for the change to propagate.
So my question is how can I change the external ip address of our exchange server to go to one of the 2 ip addresses that we already listed with our external spam filter company?