Every prospect in LeadFuze has an email status. The most high-level statuses are "Emailed" and "Not Emailed", emailed prospects can also have a status of "Opened" "Responded" or "Clicked". Prospects can also have an email status of "Bounced" if the email address bounces or "Unsubscribed" if a prospect opts out or if they ask you to remove them from your list you can edit their status to Unsubscribed.

At any given time a list will be a combination of prospects that have already been emailed your sequences, in which case they will have a status of Emailed or prospects that have not been emailed your sequences, in which case their status is Not Emailed.  Prospects with a status of Not Emailed are available to be pulled into a sequence based on your schedule. 

When a prospect is sent a sequence their status changes from Not Emailed to Emailed. Once a prospect's status changes to Emailed (or a variation such as Opened, Clicked, or Responded) those prospects will no longer  enter a new campaign unless you edit the prospect status back to Not Emailed. This way you don't have to worry about a prospect receiving the same email or being emailed more than one outreach campaign.