Is there any way to configure multiple IP addresses within DNS for a single domain record? I have a client with an SBS server and this can be reached on two different IP addresses (primary and backup ADSL services). The normal way to do this would be with multiple MX records, but this is not possible here because mail is initially going through external spam fllter servers hence the MX records point there instead. Unfortunately the spam filter service has no automatic failover capability so I'm looking for a way to do this within DNS.
Is there way to configure host records such that a single URL (e.g. mailer.company.com) can resolve to multiple IPs? More importantly, can this be done in a way such that one address is primary and the other is only used if the primary is not reachable?