Is it possible to use the API to update Leads on a specific smart list? For example, I have a smart list called "unengaged". I'd like to periodically call Marketo and update 3-4 fields for only those leads on the "unengaged" smart list. Is that possible?
No way I know to do it directly, but there are a few approaches that you could use:
Have a webhook in a trigger campaign that sends out a request to your system registering someone as "unengaged" whenever they qualify. Then you can periodically update those folks. You may need another webhook to unregister them.
You can set a field on the lead and then use the getLeadChanges API to poll and "listen" for someone matching the requirements of that list, and then update those folks.