How does blocking someone in chat work?

Direct Chats

Blocking someone in a direct chat hides their previous messages from the conversation and makes it so that you do not see any messages they send you while they are blocked, but these messages are still technically delivered. Unblocking them reveals all of their messages – including those they sent you while blocked.

To block someone in a direct chat, long-press on their name from the list of chats and select Chat settings. From here, tap Block user and select Yes, Block on the subsequent pop-up. Once done, you will see a message letting you know "This user is blocked" both in the chat list and the conversation feed. To unblock them, follow the same steps but this time you will instead see the option to Unblock user in the settings.

Chat Groups

Blocking someone in a chat group hides their previous messages for you from the conversation feed and makes it so that you do not see any of the messages they send in the group while they are blocked, but unblocking them reveals all of their messages in the feed – including those sent while they were blocked.

To block someone in a chat group, just tap the profile icon of the person you'd like to block from either the group conversation feed or the member list in the group's chat settings. This brings up a set of actions from which you can select Block user > Yes, Block. Once done, you will see the person as "(Blocked)" in the member list. Repeat these steps to unblock them, selecting Unblock user from the actions instead.