Sorry, but this is a collaboration suite, not just an app. I'm in no way associated with Zimbra but I think you didn't really understand what Zimbra is.

Zimbra is similar to Exchange with OWA. If you don't know what that means and/or have never installed Exchange + OWA, don't even *bother* thinking about considering the option of installing Zimbra.

This is very specific server software and needs an administrator to install - a really good systems administrator with Unix experience. So if you are looking a drag-and-drop-installable groupware (there is no such thing), then this is definitely the wrong app for you.

Zimbra is really nice, you can just go to the website and check it out, there is a demo-version installed where you can test it and see if it could fit your companys requirements and then tell your sysadmin to have a look at it and see if he can install it.