eGroupware is flexible and free to use collaborative software, which will help you to interact easier with your team members. eGroupware provides built-in tools like group calendar, address book, e-mail, accounting, inventory, and more. These tools provide a common user store and a flexible access control system to control information sharing.
phpGroupWare is a web-based collaborative application, written in PHP. It also comes with many pre-configured applications, like calendar, address book, todo list, notes, email, newsgroups, file manager, etc.
EgroupWare and PHPGroupWare run on a Linux or a Windows web server with PHP and a MySQL database. For the email operation, you would need SMTP, POP3 or IMAP Servers. All these are available on the SiteGround web hosting package.