See also: How to Block Unwanted Text Messages on Samsung Galaxy S3
While you're on spam message settings section, you can also enable block unknown sender option to block incoming message from the number that haven't been added to your contact list. The message from the registered number will be considered as spam message and will be redirected to the spam folder.
How to block unknown sender from sending you a message?
Here are the steps you need to do:
- Go to Apps through Home screen.
- Tap Messaging.
- Tap the Menu key.
- On pop up menu select Settings.
- Make sure you've enabled Spam Settings under Spam message settings section. When the checkbox next to this option is ticked means the option is enabled.
- Tap Block unknown senders. When the checkbox next to this option is ticked means the option is enabled.
- Tap Home button to return to the standby mode.
By enabling block unknown senders option on the messages settings, now your phone will consider that all incoming message from unknown sender are spam messages and will redirect it to the spam folder. So, did you have enabling this feature on your Galaxy SIII?