When you come to add people to an email campaign the numbers might not add up and match. This could be because of several different reasons: -
1. Not everyone might have an email address on your contact records
2. You might not have added permissions to them all - Click here to find out how to run an update many
3. People might have opted out of your communications - Please can unsubscribe, complain or even just bounce from your campaign. It is always best to check your suppression list (Go to Email > Suppression List) to see how many people are one there.