We have a VPS mail relay which we send all our outgoing mail through. It's more reliable than using our ISPs relay, and allows us to send our e-mail newsletters out more consistently.
I've currently got "Relay MTA for external delivery" set in Global Settings, it's been working perfectly for the past year.
Today I noticed there's the possibility to add additional values!
So I could set the SSH tunnel to the relay as the 1st relay host and the static IP as the 2nd.
So if the SSH tunnel is down it will use the 2nd choice relay host?
Is that what it's designed for?