Instead, manulroute appears to be believing that it has a higher
preference than the lowest preference returned from DNS? At least
when the local host is removed from the list, everything other than
the highest preference MX in the entry before it gets removed. So
basically when it removes backup.server.com it also removes
mail2.domainname.com from the list. Removing mail2.domainname.com
would make complete sense to me if I had a manualroute entry like: