Blocking someone

Right-click a person and choose Block. Blocking is invisible to them.

What blocking does

• Their messages collapse behind a Blocked message row. Press Show to read one.
• They cannot DM you, and you cannot DM them.
• They stop being able to ping you with mentions.

In group chats and boards you still see their collapsed messages, since the conversation has other people in it.

Unblocking

Settings, then Privacy, lists everyone you have blocked. Unblock from there.