I'm with the IT dept for a firm of about 30 OS X systems and 1 XP system running a mix of Eudora, Mail.app and now some Entourage. We also have some Blackberry's active as well. Our current mail system leaves much to be desired. It's a POP3 system with SpamAssassin. I'm looking for a package that will allow sharing of calendars & contacts. Zimbra looks very promising but I'm curious how well it plays with a client such as Entourage. I'm looking to overhaul our mail environment by implementing a new server along with a standardize of our mail client. We don't want to have to rely on a web browser though, but have it available as an option for out of office and whatnot. Any experience with Macs you can share is much appreciated!