Does Samsung Galaxy S II show any indication that sms sending is complete? If I send an sms from Samsung Galaxy S II, it just shows a toast message saying Sending Message... which disappears in a few moments. Is it possible to set it to show some kind of confirmation that the sms sending is complete? Or ss this dependent on the telephone company?
Open the message thread in the Messages app and it should say "Sent" and the time at which it was sent.