What about starting with Zimbra's Open Source edition, and building onto it?
On Tue, Jun 7, 2011 at 9:13 PM, Santino Codispoti < santino.codisp...@gmail.com> wrote: > Does anyone happen to know what Microsoft using to delivery Hotmail? > Is it Exchange? Can anyone recommend a good system for developing web > mail services? I need something that can easy support 400K users > >