Hey, thanks for reading up on my little challenge. If it's not too much of trouble, I'd appreciate it if you could point me in the right direction! For my main site, which runs on CakePHP and integrates XenForo (it also makes use of the xf_user table), I have created an Event system. I would like to add <custom> alerts to the author of the Event when people RSVP (= they list themselves as Going/Maybe) to the event or leave a comment. How is this achieved in the easiest way? Do I need to write a small Addon to support this? Where would I best start?