I have a Nokia 6225 (CDMA) and have a problem with message overwriting. The options are "Sent items only", "Inbox only", "Sent items & inbox", and "Off". I would have thought that "Sent items & inbox" was the logical choice ie. the oldest message in either the sent items or inbox is overwritten when either a new message is sent or one is received. What seems to happen though is that the sent items are overwritten until there is only one left which continually gets overwritten. I haven't checked the exact operation but it seems to operate similarly to if "Sent items only" is selected.
Am I misunderstanding this setting or is there a bug with the phone?