We have an onsite Exchange server that handles all or our mail. We have a single MX record in DNS that points to it. I want to have a backup mail server through our ISP in case something ever happens to our primary. Can i just create a secondary MX record with a lower priority for the backup mail server? How does that work....all email will still go to our primary mail server and when it becomes unavailable for whatever reason, all mail starts routing to the secondary mail server until the primary comes back online? Thanks in advance!