I work as an I.T. for a company with about 400 office employees. We are currently looking at deploying openoffice.org on some of our machines, and also an email system to replacement Outlook 2000. At the moment, we have some alternatives like Barca or thunderbird, but we could also potentially move away from M.S. exchange.
Any suggestions on a viable email system, preferably one that is low-cost or free. We need exchange like functionality and a decent outlook-like email client.
Thank you in advance.