You might encounter the following situation: created a segment and a newsletter campaign with the same conditions and there is a difference between the user count number.
As you can see there is a small difference between the two. The reason is because for each campaign type we add by default some extra conditions to make sure we don’t send emails to users who are not subscribed (or clicked spam in the past).
The following image shows the minimum required conditions for a newsletter to be sent. Event when you delete them, we add all these back to keep your sending reputation up.