How do I mention someone in a Spark post or comment?
To mention someone, type @ followed immediately by the person’s name and select the correct person from the list that appears. Don't include a space between @ and the name.
As you begin typing the name after the @ symbol, the list will appear right away with all of the people who match what you have typed. Continue to type out the full name to reduce the list of people in the list until you are able to find the correct person you would like to mention.