To notify everyone in a Slack channel:
To notify everyone in a Slack channel when you send monitor notifications to that channel, you can add <!here> in the monitor message editor and it will be populated to @here in Slack.
Other variables you can use are:
- <!channel> ->@channel
- <!everyone> ->@everyone
- <!group> -> @group
- <@username> -> @username
To notify everyone in a Hipchat room:
To notify everyone in a Hipchat room when you send monitor notifications to that room, you can add @here in the monitor message editor.
Note @all mention is also supported by Hipchat. However, we recommend you to only use @here here since in Datadog monitor, if you add @all in the message editor, the monitor will send a notification to all members of your organization.
To get notified by @here mention, Hipchat users need to set Room notifications to Normal level.
You can read here about how to send monitor notifications to Slack and Hipchat services.