Can I have two SMTP Public IP Addresses put into the “Relay host for messages leaving the local internet domain” field in the “Basics” Tab of “Router/SMTP” in the Server Configurations in the Domino Directory.If so how is this done?. These two SMTP Public IP Addresses belong to two different service providers.
Read through David Bell’s terrific article; It may help with what you are ultimately attempting to do.IBM Developer
To answer your question directly, if you control your DNS, you can set up a couple host (A) records for the appropriate servers. This will round robin between the addresses on each lookup. For example