We've been using Atmail (http://atmail.com http://atmail.com) for some time (self-hosted) for my company. Works great. They offers a hosted service too now. Nic

We've been using Atmail (http://atmail.com http://atmail.com) for some time (self-hosted) for my company. Works great. They offers a hosted service too now. Nice UI/UX and offers full calendar/contacts and Push.