Google has confirmed automatic spam protection is coming to the the Messages app and has already begun rolling out to some users.
First spotted by Android Police, the feature will automatically detect and block messages from spam senders or telemarketers just like competing apps such as SMS Organizer by Microsoft do.
Automatic spam protection will be opt-out so you have to toggle it on in the settings. In a statement provided to The Verge, Google said that it will temporarily "store phone numbers of people sending and receiving messages with you and the times they messaged with you", but it also added that it does not store your number or the message contents.