Mute a topic

Messages from muted topics do not show up in All messages or generate notifications (including alert word notifications), unless you are mentioned. They also do not contribute to stream unread counts.

Muted topics still appear in the left sidebar, though they are grayed out.

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On the left, click on the stream that contains the topic you want to mute or unmute.
Hover over the topic to reveal a ellipsis () to its right. Click on the ellipsis ().
Select Mute the topic <topic name>.

Follow the same procedure to unmute the topic.

From the message view

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Find a message belonging to the topic that you wish to mute or unmute.
Hover over a message to reveal three icons on the right.
Click the ellipsis ().
Select Mute the topic <topic name>.

Follow the same procedure to unmute the topic.

See your list of muted topics

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Go to Muted topics.

From there, you can also unmute any muted topics.