Why ZReminder? Why not use my phone?
You could use an app on your phone to do this. Of course when you lose your phone or change your number or change providers or or or or - no or's with ZReminder, it just keeps working.
Out of sight, out of mind - until it's time to send the reminder!
ZReminder is just plain and simple. Send a reminder every X days. Or every X months, or once a year, or X years.