Workfow Manager > How to avoid Send Campaign Email Error: You are attempting to send the same campaign email twice to the same recipient

Question: How to avoid a Send Campaign Email error from campaign emails being sent via the Workflow Manager.
 
Answer: The error received is an intended NetSuite behavior. To avoid this, filter out the leads or prospects that the workflow is working on. For example, create a custom checkbox where on initial entry into the workflow, perform a Set Field Value (set to True) on the custom checkbox. The workflow should only initiate to leads or prospects that were tagged as False. Avoid leads or prospects to enter the workflow twice.