I have a SFDC formula field on an opportunity that's causing daily updates to Marketo leads. I'm just finding out that we can't block opportunity fields from updates? And we cant delete mappings... and we can't delete fields... Am I right?
That strikes me as odd because to my knowledge, Marketo does not treat formula fields as data value changes.
You should be able to use field level security to hide that from Marketo and then you will need to hide it from the interface in Marketo also.
Dane, just ensure you are not blocking fields that will prevent other things in Marketo from working. If you have a lead lifecycle program, for instance, and stages which react to opportunity updates, you will want to ensure those activities are still recorded.