Mark messages as unread#
 Available on 
all plans
 
Cloud and self-hosted deployments
If you read a message, but donβt have time to address it right away, you can mark that message as unread. Marking a message as unread displays the channel as bold in the channel sidebar, and groups the message with all other unread messages.
Hover over the message, select the More  option, then select Mark as Unread.