Open History > Group Messages and click the broadcast's ID. The detail page shows "X / Y sent" in the header, the creation time, the scheduled time and the message body, followed by a Sent table (#, Contact, Sent on) and an In Queue table for recipients still waiting. For per-recipient delivery status open History > Sent and search by the message text or phone; each row's Status column shows queued/sent/delivered/failed/undelivered, and clicking the ID shows the error code and the Balance History for that message.