Evolution is the official personal information manager for GNOME.

SugarCRM is a customer relationship management (CRM) system.

Memotoo sync all your contacts from Gmail, Facebook, phone, Thunderbird, Outlook, etc in a single address book.

AdiInviter Pro is a contact importer and tell-a-friend platform.

Claws Mail is a free and open-source, GTK+-based email and news client. It offers easy configuration and an abundance of features.

Kontact is a personal information manager and groupware software suite developed by KDE. It supports calendars, contacts, notes, to-do lists, news, and email.

Stoq is an open source framework for enterprise level automated analysis.