This behavior is probably related many factors :
- blacklists: on every sending, Splio don't consider contact users who no longer want to receive communications (contacts in blacklist).
- natural unsub : contacts may choose to unsub themselves from your lists using the unsub link. Thus unsubscribed contacts may be removed from the final target
- deletion of duplicate entries: when the target is built with several temporary files, Splio removes duplicates entries to avoid sending several messages to the same contact.
Usually these three factors may result in a gap between target expected and the final one. In most cases, natural unsubscription is the main explanation of this unexpected result and this is why we recommend to follow up on the evolution of subscriptions of your database.