Home-Assistant.io - Home Assistant is an open-source home automation platform running on Python 3.
SendRecurring - SendRecurring allows you to setup, send, and maintain scheduled email reminders.
ioBroker - flexible and modular application for the IoT and Smarthome
Recurrr - Send recurring emails
openHAB - "empowering the smart home" - vendor and technology agnostic open source home automation
Followup.cc - FollowUp for email is a lightweight productivity suite that keeps your conversations and tasks from slipping through the cracks. Set perfectly timed reminders that arrive at the top of your inbox, right when you need them.