How to restrict stranger messages in WhatsApp How can I restrict other WhatsApp users from messaging me, who are not in my mobile contacts. Me and my friend have given a try by simply deleting my fiend contact number from my mobile, and he's still able to send me message in whatsapp-messenger.

So, is it that, anybody can send messages to anyone in the world, provided if they know the mobile number? If so, where is the privacy? Is there a setting option?

Do I have only one option to block them? I would like to see only people in my contacts list message me.
There's no method of blocking messages

Ex:Let's say you receive a message on what's app from an unknown number not in your contact list.Whatsapp will undoubtedly display that message as it's functionality say's so.

Once you have received the number you are aware that the number is unwanted and you can block it.
Note:-Here you are only blocking the number from seeing your last seen,read,display picture,name but it will not refrain/stop the number from sending messages.

There is no feature in what's app to block any number from sending messages.The feature may be added in the upcoming updates