Zimbra - Zimbra is trusted by over 500 million users to increase productivity with a complete set of collaboration tools while maintaining total control over security and privacy.
HEY - Email at its best, new from Basecamp.
Google Workspace - Google's encompassing suite of cloud-based business apps.
Horde - Horde Groupware is a free, enterprise ready, browser based collaboration suite.
Microsoft Exchange Server - Microsoft Exchange Server is a messaging and collaborative software product developed by Microsoft.
InstAddr - Disposable email address application.