Accept or block chat requests from people inside your organization in Microsoft Teams
When you receive a message from a new internal contact, you have the option to accept or block messages from that person, as long as your admin has assigned this policy to your team.
Choose Accept to start a new conversation. If you choose Block, the sender will not be notified that you blocked them, and you’ll no longer receive their messages.
To block a sender in an existing conversation, hover over the chat in the chat list, and select More options > Block.
To unblock a person, hover over the chat in the chat list, and select More options > Unblock.
You can also hover over the person’s profile picture, and when their profile card appears, select More options > Unblock contact.
This feature only affects one-on-one chats from other people inside your organization, and doesn't affect chats in groups, channels, or meetings.
Learn more:
Accept, block, or delete chat or meeting requests from people outside your organization