WhatsApp has received plenty of new updates over the past year or so. The most recent update for Android involved the addition of a new Material Design user interface, keeping in line with Google's UI philosophy.
It seems like WhatsApp has also made some under the hood changes to the app, with the addition of a new 'report spam' feature. This has been spotted on both Android and iPhone versions of the app.
This feature lets you block and mark users as spam if you feel they're coming from a marketing agency and not individuals. Alternatively if you know the users, you can add them to your contacts. If you simply want to block a user and don't want to report them for spamming, you can do so by heading over to the settings button on the top right of the screen and tapping 'Block'.
This is a very interesting feature and will ensure that you aren't spammed with marketing messages on a regular basis. WhatsApp already had a similar system in place where it automatically blocked users from its database after a select number of users have blocked them, thus treating them as spam. But this is for the first time that the developers have made this feature more prominent and visible to the users.
The feature should be available on the latest version of WhatsApp, which at the time of this writing is 2.12.56 (Android), so make sure you download it from the company's official site to test out this new feature for yourself. The addition of this feature should reduce the likelihood of marketing teams bombarding your inbox with unnecessary messages.
[Source]