
Description: Courier-MTA is an open source mail transfer agent (MTA) used for sending, receiving, and routing email. It is designed to be fast, scalable, and flexible with high throughput.
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