Notifications: I’m getting too many, or not enough
Notifications can be set for the whole app as well as for each channel individually. You can also configure Do Not Disturb (Notification Schedule) times so you can silence notifications automatically between certain times every day.
App notifications
App notifications are found in the You tab. It’s recommended you set the following to ensure you are notified immediately for messages:
On Mobile, notify me about… All new messages
Notify me on mobile… Always, even when I’m active.
Notification Schedule
You can choose to pause notifications during specific times (e.g. at night). If you want to receive notifications all day every day, set Notification Schedule to ‘Every day’ with the start and end times being 12 AM

Channel Notifications
You can mute individual channels or reduce the notifications you receive. For example, you may want to turn off notifications for the #random or #general channels.
From the Home tab, select the channel you want to change. Press the i icon at the top, and set your notification preferences for that channel.
Other Troubleshooting
If you’re still having problems with receiving notifications, try the Notification Troubleshooting option on the You tab > Notifications.
Android Users – some devices put Slack to sleep from time to time. Refer to Slack support pages to see if you can whitelist or exempt Slack from Battery Optimisation.