
Description: AtMail Open is an open source email server software designed for high delivery performance, security, and reliability. It is based on open standards and is a scalable on-prem email platform for SMBs.
Type: Open Source Test Automation Framework
Founded: 2011
Primary Use: Mobile app testing automation
Supported Platforms: iOS, Android, Windows

Description: Zoho Mail is a free, ad-supported email service that provides enterprise-level features for individuals and businesses. It offers unlimited storage, POP and IMAP access, mail forwarding, shared calendars, docs and more.
Type: Cloud-based Test Automation Platform
Founded: 2015
Primary Use: Web, mobile, and API testing
Supported Platforms: Web, iOS, Android, API