Microsoft Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.
Acompli - iPhone email just got a promotion
Gmail - Gmail is available across all your devices Android, iOS, and desktop devices. Sort, collaborate or call a friend without leaving your inbox.
Send - Instant messaging meets email (by Microsoft)
Thunderbird - Thunderbird is a free email application that's easy to set up and customize - and it's loaded with great features!
Brosix Instant Messenger - Secure instant messenger for your team