Why do some recipients' views have a red asterisk next to them?

An inferred view (indicated by a red asterisk in Reports) is a special type of unique view that is recorded when a recipient has images disabled or blocked (meaning a unique view was not initially recorded when they opened the email) but the recipient takes an action with the campaign such as clicks a link, downloads a file or opts out.

In these cases, the system inferred that in order to click, download or opt out, the recipient had to view the campaign - so in addition to recording the specific action(s) taken by the recipient, a unique view is also recorded.