I have dual ISP connections to my ASA with the monitor on the "outside" interface so that when it fails, it will switch to the second default route. This is great for outbound traffic.
I have an exchange server behind the ASA with the 192.168.X.X static of the Exchange box NAT'ed to one of the primary ISP's provided statics 51.2XX.XXX.XXX.
In the event of a failure of the primary ISP's WAN link, it would be nice if email would continue to flow to our Exchange server via he failover WAN link with a different group of static IP's. Is it okay to do that?
What I envision is adding an MX record with a higher value to the other routable static IP and then simply putting the NAT rule in for that.
Any suggestions on how best to do this?