I know Zimbra is an all in one solution, which is unfortunate, but a reality at this point. I wish there was a modern open source groupware solution, that didn't take an all or nothing approach.
Keeping this in mind could I setup Zimbra to exist as cal.bigcorp.com and have accounts on Zimbra, but have all the messages forward to accounts on mail.bigcorp.com?
Finally, could I have the calendar pop up as the default view on login? Is it possible to remove the mail view?