This is not an automation or coding question.
This is a procedural question, i.e., "how to". I have researched through functionality, documentation and support questions/answeres and yet found no solution.
I have 4000 leads and contacts. I have run three previous campaigns, each campaign was a combination of leads and contacts, some leads and contacts were in more than one campaign. I now want to select a certain sector of leads and contacts (I can do this by identifying various field values for the records) that are NOT included in any of the previous campaigns or perhaps just one of the previous campaigns. How can I dot this?