That actually might be someone expensive to implement. To send an immediate notification is fairly simple to generate, after processing the page with the request, send the notice, and all is done. The forum software is already active at that point, so not much work. To send on a 5-minute delay, then the software needs to start up periodically, (like once every 1-5 minutes depending on how tight you want the 5-minute delay to be) and then check to see if there is a pending request for a notice that is now old enough to do and then send it or wait a bit more. So you need to add the whole new procedure, and it needs to run fairly often.