
Description: Exim is an open source mail transfer agent (MTA) developed for use on Unix systems. It is lightweight, flexible, and one of the most popular MTAs for Linux and BSD systems. Exim aims to be secure, scalable, and easy to configure.
Type: Open Source Test Automation Framework
Founded: 2011
Primary Use: Mobile app testing automation
Supported Platforms: iOS, Android, Windows

Description: Postfix is a popular open source Mail Transfer Agent (MTA) that routes and delivers email. It is a fast, easy to administer, and secure alternative to Sendmail. Postfix handles basic email routing and delivery well.
Type: Cloud-based Test Automation Platform
Founded: 2015
Primary Use: Web, mobile, and API testing
Supported Platforms: Web, iOS, Android, API