Mark All as Read in Slack and Teams: Unreads and Catch Up
Back from time off to hundreds of unread messages? Both Slack and Teams have a dedicated catch-up surface, but they are not the same tool. Slack's Unreads view works on desktop and mobile and includes a true mark-everything-read button. Microsoft's Catch up is a mobile-only, card-by-card triage. Here is what each help page documents.
Miles Crawford
The quick version
In Slack on desktop, open Unreads at the top of your Home sidebar, then scroll to the bottom and click Mark All Messages Read to clear everything at once. In Teams, tap Catch up at the top of your chat list on mobile and swipe right through each conversation card to mark it read; there is no one-tap clear-all in Microsoft's article.
Slack: the Unreads view on desktop
From Home, click Unreads at the top of the sidebar; if you do not see it, a sidebar preference can pin it there permanently. The view lists every conversation with unread messages, and you can react, start or reply to a thread, use message actions, or click a timestamp to jump into the channel or DM. You cannot send a new message from the Unreads view itself, but hovering a message and opening the three-dots menu gives you save, share, react, pin, remind and thread actions. A Sort menu orders the list like your sidebar, alphabetically, in a recommended order, or by newest or oldest activity, and a Filter menu narrows by sidebar sections, including custom sections on paid plans. Sorting and filtering are desktop only.
Slack: marking read, undo and shortcuts
Click Mark as Read to clear one conversation, or scroll to the bottom of the Unreads view and click Mark All Messages Read to clear the lot. Clicked too fast? Undo restores the conversation to the view. The arrow icon beside a conversation name collapses it so you can come back later. Keyboard shortcuts speed the whole pass up: Cmd+Shift+A on Mac or Ctrl+Shift+A on Windows opens Unreads, Esc marks a group of messages as read, Option+Click or Alt+Click marks a single message unread, and the arrow keys move through and expand or collapse groups. On mobile, the same idea lives in Catch up: swipe right to mark a conversation read, press and hold Mark as Read to clear all, swipe left to skip, and tap Undo if you went too fast.
Teams: Catch up on mobile
Microsoft's Catch up is available on mobile devices and pulls together the conversations that need your attention: personal mentions wherever they appear, 1:1 chats, group and meeting chats unless muted, and followed threads. Tap Catch up at the top of your chat list and each conversation appears as a swipeable card with full context, so you can read, respond and react without leaving the view, or mute and unfollow from the card header. The number of cards is the number of conversations between you and a zero badge count.
Teams: triage one card at a time
Swipe right on a card to mark the conversation as read, swipe left to keep it unread, or use the Mark as read and Keep unread buttons at the bottom of the screen. Undo at the top brings back the previous card, the dropdown next to the chat or channel name offers Mute, Unfollow and Go to conversation, and Sort by can show @Mentions first or order by most recent. Read and unread states sync across mobile and desktop, so progress carries over. When every card is cleared, Teams shows You are all caught up, and a dot badge flags anything new that arrives later.
Which one for what?
Our read: if the goal is a true inbox-zero reset, Slack is the stronger tool because Mark All Messages Read clears the whole backlog on desktop in one click, with keyboard shortcuts for the manual pass. Teams Catch up is a gentler triage: it forces a decision on each conversation, which suits people who do not trust a blanket clear, but it lives on mobile only and muted chats and threads you do not follow stay out of the pile entirely.
What to be careful about
- Mark All is a Slack desktop move. On Slack mobile you press and hold Mark as Read inside Catch up instead.
- Teams Catch up is mobile-only. Microsoft describes it as a mobile feature; desktop has no equivalent view in that article.
- Undo exists in both. Slack restores a conversation to Unreads; Teams brings back the previous card. Act fast, then undo if needed.
- Muted Teams chats are excluded. Group and meeting chats only appear in Catch up if they are not muted.
- Slack sorting and filtering need desktop. Paid plans can also filter by custom sidebar sections.
- Slack mobile Catch up does not live-refresh. Reopen it to see new unreads; desktop shows a syncing arrows icon instead.
Sources
Checked October 24, 2026. Features, steps and shortcuts follow each product's own help articles. The guidance on when each shines is ours.