Mailu - Mailu is a simple yet full-featured mail server as a set of Docker images.
HEY - Email at its best, new from Basecamp.
Microsoft Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.
Horde - Horde Groupware is a free, enterprise ready, browser based collaboration suite.
MailEnable - MailEnable is a Windows based mail server and email server program that is packed with the state of the features and functions like antivirus and spam filtering system, webmail management system, cardDAV, CalDAV and much more.
InstAddr - Disposable email address application.