notify.el

(define-jabber-alert macos
  "Displays message using terminal-notifier app on Mac OS"
  'terminal-notifier-notify)

(defun terminal-notifier-notify (message &optional title)
  "Show a message with `terminal-notifier-command`."
  (start-process "terminal-notifier"
                 "*terminal-notifier*"
                 "reattach-to-user-namespace"
                 "terminal-notifier"
                 "-title" title
                 "-message" message
                 "-activate" "org.gnu.Emacs"))