Domino as MX backup "store and forward?"

I’m wondering if it’s possible to setup Domino 6 as a store and forward system, to serve as a backup MX for a domain.

Using example test.com, mx records would look like:

10 primarymailserver.test.com (Sendmail)

20 secondarymailserver.otherdomain.com (Domino)

Where I own secondarymailserver.otherdomain.com. So mail not being delivered to *@test.com because of server outage could route to our Domino server, then be relayed out to test.com when the server is up.

Thanks all!