If you are sharing private information like contracts for designs and designs that aren't meant to be shared only with one client, the platform is very secure
Zimbra is great for an email system for a medium or large organization with appropriate IT staffing. The system is easy to use for end-users, and has a fantastic web interface. Unfortunately, it is overly complex, when considering staffing requirements and price, when compared with Office 365 or Google Apps for smaller organizations. For other education customers, it is hard to compete with Microsoft and Google providing their services for "Free" now though
Huddle allows users to use the native document file types. For example, Word files are still in a Word, not a "Huddle" file version.
Huddle workspaces are invitation-only. If someone should not be in the workspace, they will not be invited and provided access to the documents. Or, they can be removed from the workspace if needed.
Communication about documents is located with the documents in a discussion thread under the document preview. Thus, email inbox clutter can be limited.
The password change is not activated when you access by IMAP, Pop3 or Exchange sync. You have to know that the password change is required and you must go to the website to do so.
The management of mail rules should have more checking options.
There should be more applications compatible with Zimbra, the ones that appear in the Zimlets.
Overall, we were satisfied with the implementation. We perhaps should have spent more time consulting with Zimbra or others regarding best practices but as we got to know the system better we were able to make changes relatively easily after the fact.
Sharepoint is very flexible, but very clunky and slow when all one needs is a quick document management solution. M-Files is a great, rich document management system, but until recently focussed less on the collaboration piece.
We selected Zimbra because it has a lower cost in the market, offers more development features for its open source, has a very easy to use interface and adjusts to the needs of the company.
Since all of our ROI studies and strategies are performed at the corporate level, I'm really not sure what positive or negative impacts Zimbra has had on our overall business objectives. I can say that at least one positive impact it has on my business objectives, in the medical record department, is the ability to be as paperless as possible.