You can notify a group of users in your system from a single message using the Message matrix to send a message, for example, if you want to send a notification about the top Kudos points.
To target only the users who have logged to your portal at least once, apply the filter User Login Count then choose Larger than or Equal to 1. Click Add.
Once you have sent the first message once, you can reuse the message. In the Messaging Matrix, click Show History on My Messages send, select the relevant message, edit and resend it.
