Teem - Cloud-based meeting room booking system
Thunderbird - Thunderbird is a free email application that's easy to set up and customize - and it's loaded with great features!
AskCody - Meeting management system for Outlook & Office 365.
Geary - Geary is an email application built for GNOME 3.
TractionGuest - Safe, secure workplace for all.
Evolution - Apps/Evolution - GNOME Wiki!