Email campaigns, marketing list size, and excluded emails

I was wondering what reason there would be for the number of sent emails to not equal the number of emails on the marketing list, if none were excluded?

I have an email campaign that was being sent to 2 marketing lists. They total 107 emails. In the statistics report, there were no exclusions. Yet, there were only 96 emails sent. No bounces either. I checked, and all people in the marketing lists have emails.

Is there another reason it wouldn't show there were 107 emails sent?

Thanks!