Has anyone ever imported an email list with leads that could only be emailed once or very limited times? If so, did you use any different fields upon import to keep this list seperate from the other leads in your database?
seems like this is a list from a Partner...I would use the naming convention of the list to keep it seperate...the key will be not to sync it to the CRM when you add it to a program. In the past I have even used a flow-action to unsubscibe all of the people on a list just one minute after the one program they were in went live...