A smart list consists of a 'Was Sent Email' filter with Email is any' and...

A person would not appear on this smart list if the email sent to them last week bounced. This is because a bounced email is not considered as a sent email in Adobe Marketo Engage. Therefore, the person would not meet the criteria of the Was Sent Email filter and would be excluded from the smart list. The person would appear on the smart list if they were last sent an email 6 months ago or if they unsubscribed from the email they received last month, as long as they met the date of activity constraint