I'm currently evaluating Zimbra to replace Groupwise. One important feature that we require is the ability to "proxy" into another account to view the inbox and/or calendar. This is particularly important for secretaries who need to maintain an executive's appointments. I didn't see anything like this in the 4.5 demo. Does it exist? If not, will it be in v5?
Sharing passwords is not an option. It is important to be able to set permissions so a secretary could not view email... only calendar, for example.