Scheduled notifications. Post now, but receive later.

I would like some delayed delivery option.my reasoning: quiet hours are good and well and for emergencies I use emergency priority, but among my use cases is the following: I have self written IMAP client running 24/7 which sorts and analyses mails and generates notifications. Quite a few are below “need to see immediately” but in the “see first thing in the morning”. As such it would be great if I hadn’t have to check the pushover app but just get them delivered when my quiet hours end. For my main use case I implemented it myself by writing my own scheduler of sorts. 

And the same process could be used to implement the also requested heartbeat feature. Schedule a message, get a  token, cancel that before it gets send.  A minimum wait period of one hour should suffice (everything else need real time monitoring by your own servers, guys).