WhatsApp is studying some methods to prevent spam

Nowadays, the spam is a very widespread phenomena, and it is unfortunately also present in WhatsApp, starting to unknown contacts that add you in new groups, or when you receive spam messages like this:
WhatsApp is going to cost us money soon. The only way that it will stay free is if you are a frequent user i.e. you have at least 10 people you are chatting with. To become a frequent user send this message to 10 people who receive it (2 ticks) and your WhatsApp logo should turn Red to indicate a frequent user.

This is absolutely false, but not well-versed users may believe to these messages, or they may be bothered for them.

Read more