I am thinking about a migration from Exchange. My customer's upper level management requires to use Outlook, while ordinary users can use any IMAP client. Can anyone please help me answer these questions:

1- If managers use Exchange, and users use Zimbra. Will they be able to see shared calendar, and set meetings transparently from outlook/web_or_ical ?

2- If I choose to run a Network edition server for managers, and an OSS server for users. With managers using Outlook to connect to their server. Again, will the two mail servers be able to exchange calendar entries ?

Finally, you have a really good product. I beleive your licensing scheme is not flexible enough though! It is either all or nothing!! IMHO, with a cost of 75% of Exchange, this is not next to compelling to migrate from Exchange.
I think you need to allow some user accounts to be network-edition, while others are not (and not benefiting from some advanced features)

Best Regards
Keep up the excellent work