I have a Nokia x2. and unfortunately it does not have any “mark all” feature. It’s a real headache to delete messages one by one. So I am looking for any SMS inbox manager (.jar file), so that I can use the mark all feature.
To delete messages all at once use Nokia PC Suite and connect your X-2 with your PC via Bluetooth
I haven't used Wammu, but its description may show some promise:
"Wammu is a mobile phone manager using Gammu as its backend. It works with any phone that Gammu supports, including many models from Nokia, Siemens, and Alcatel. It has complete support (read, edit, delete, copy) for contacts, todo, and calendar. It can read, save, and send SMS. It includes an SMS composer for multi-part SMS messages, and it can display SMS messages that include pictures."
Let us know if it worked!