There's two options to fix this.
1. Go to Exchange System Manager and locate SMTP properties.
You will likely have an IP address specified. If you change this to 'All Unassigned' then rescue will work.Stop and start the service (wait a minute for it to work). If you want to keep the IP address specified then go to option 2.
2. Go to Settings>>Setup>>System Configuration, and in the 'Web Hostname' box, enter the IP address above.