Zarafa has several very valuable features, among them a very good Outlook-like web interface.
Furthermore, ZPush for talking between ActiveSync and mobile devices is a valuable asset.
In addition, one is able to connect via Outlook and the exchange protocol to Zarafa. This makes Zarafa a free, and working, alternative to Microsoft Exchange.
Improvements to My Organization:
I mostly installed Zarafa for customers. They found it to be a lightwight groupware solution with many enterprise features, such as connecting to Active Directory or OpenLDAP.
Room for Improvement:
As far as I know, only MySQL is supported. It would be great to also have Postgres support, but I am not sure if this is possible in a technical way because Zarafa has very specific requirements when it comes to storing MAPI objects in a database.
Use of Solution:
I was using it for more than two years.
You should be aware that Zarafa will create a lot of database entries, so you should tune MySQL (especially the InnoDB options).
Not really, although the Zarafa-index component was using a lot of memory and disk I/O bandwith.
I used Kolab, but connecting via Outlook was only possible with IMAP or a MAPI connector (and all of them were not working very well). Zarafa, instead, supports MAPI in a natural way.
Initial setup is very easy if you are an experienced Linux user/admin.
Disclosure: I am a real user, and this review is based on my own experience and opinions.
Jul 19 2016