When entering an @ reference for a username, the name must be surrounded by spaces. Otherwise the @ reference is left unprocessed. Examples:
"@name," << trailing comma
"(@name)" << trailing parenthesis
"@name!" << trailing exclamation
"@name: " << trailing colon
I'm suggesting regex processing to stop where it finds any character after the @ sign which is not allowed in a user name. That includes most punctuation. Thanks!