Re: [Announce] bitcoinmonitor.net - Free professional notification/payment service
But what is a problem to increse retry time to for example 1 hour and try to deliver it for next 24 hours ? It would reduce a chance of lost money if site is offline.
Well, I think you are right 
In the end it is probably better to deliver late notification instead of not at all. I will change the retry policy to retry up to one day, with an increasing time between tries.Probably it also makes sense to have the maximum retry time a user-defined setting...
Also you should make queue for sending so if you can not deliver 0 conf notification you should not try to deliver 6conf one.
Indeed this would be better. But this will require some refactoring on my side. Might take some more time...