On the Review and Confirm step the Recipients section shows a summary such as Registered User (240), Uploaded Contact (35) (275 total), calculated live from your current selections. Click View Recipients to open the Recipients Preview modal: a searchable, paginated table with ID (customer number, or blank for uploaded contacts), Name, Email and Source (Registered User, Uploaded Contact or Lead Form). The count shown (e.g. 275 recipients) is the final number after exclusions and de-duplication, i.e. exactly what will be queued when you press Send Campaign.

If no Send-to group is selected you get No recipient groups selected.