mailcow - An open source mailserver suite.
Azure Sphere - Help protect your connected IoT devices, such as MCUs and crossover modules, development kits, and guardian devices, with Azure Sphere.
Mail-in-a-box - Mail-in-a-Box provides webmail and an IMAP/SMTP server for use with mobile devices and desktop mail software and also includes contacts and calendar synchronization.
Symantec Critical System Protection - Symantec Critical System Protection is a flexible and compact behavioral security engine built with application whitelisting infused with anti-exploits for managed or standalone IoT devices.
Mailu - Mailu is a simple yet full-featured mail server as a set of Docker images.
Azure IoT Hub - Manage billions of IoT devices with Azure IoT Hub, a cloud platform that lets you easily connect, monitor, provision, and configure IoT devices.