higher open number than sent number
I try to check an email report numbers. I found a strange thing. If I create a smart list for ppl who received a particular email, I get much fewer numbers than the smart list for those ppl who opened the email
65 ppl opened (based on smart list)
31 ppl sent (based on smart list)
And in the email performance report I can see the following numbers:
209 sent
83 open
When I filter for a person, who is on the list of 'open email' and not on the list 'sent/delivered email', and check the activity tab, I can see both activity

I don't know what can I report now, these are so. different numbers. Why do you think I have this?
Thank you for your help
Kata