reminder software that reminds you by email


Does anyone know of a good software for Mac that sends email reminders on a certain date. I have to constant remind myself to do things.

It would be nice if the software had functions such as monthly reminders. For example, send me an email every month on the 25th to do something. Or to set a reminder email to fire on April 1, 2016.
iCal is perfect for that. Also when you need to send a notification for someone else for the meetings or whatever you need a reminder of.
I've been increasingly using exactly iCal for those - like on day xx.yy.zz remember to add credit to prepay phone so it doesn't expire, or some other day, pay the rent etc.
And since there are sometimes needs to repeatedly share events or reminders with certain people or groups, you can create a new calendar, and share everything with that calendar automatically with someone else.