Thoughts on Zimbra?

So I have been looking for an open source alternative to Exchange for my server. Zimbra looks pretty impressive. I want a nice all in one solution for caldav, carddav and email.

Has anyone used it either work and/or personal use? 

Do you like it?

And would it be right for me? I only need it for a few clients.

And how well does it work with various clients: squardcube, mailpile, and Thunderbird? 

If you have any recommendations on similar software please let me know 

Question: Are your clients new enough that you could get by with _only_ activesync and you don't need mapi? (hint: if only outlook 2013 and mobile devices will be used, you're golden)

then I would not do zimbra. These linux distros for this kind of thing are almost universally bad. I had high hopes for openchange.. but... well.. let's not go there.

I very recently did a deep dive with postfix, lucene, kolab, activesync, mysql and a bunch of other glue and it worked out really well. Actually, I don't know if I've leveled up a bunch in server admin or what (lol, nope -- thanks package maintainers) because I was basically able to do almost everything without really doing much other than reading the docs. So far it has been rock solid and stable.

I added on clamav and some postfix extensions like greylisting and realtime dns stuff to help cut back on spam and my god I don't think I've had a better mail server.

I then setup another one for tek that is basically the same, and we've been using it internally, and love it.

We have full calendar, contacts and email sync to a fully open backend _on debian_ so I am not worried about patches, forward compatibility and all that.

P.s. zimbra charges for your mapi connectivity and gimps activesync last I checked.

 p.p.s it also has imap for a fallback for those clients. imap is dead to me though lol. 

p.p.p.s. and for the paranoid it is trivial to put your message store on an encrypted file system so if someone snapshots your vm, unless they also snapshot ram, they're boned to decrypt your message store. Did I mention debian? Debian. apt-get your way to happiness and sanity. 

p.p.p.p.s you pretty much have to buy a real SSL cert though so you can do SSL all over the place with smtp and imap and https and blah blah blah. Perhaps our readers can give us a run down of places to get free or insanely cheap SSL certs?

Thank you for the very in dept answer. Yeah using Kolab and the other tools you mentioned does sound like a better idea

The only thing is that I am not a full on pro  on setting up web services. But I am able to read documentation and follow instructions. Maybe a video..........if you have the time of course.

Client Side I was going to use thunderbird and mailpile for webmail.  If mailpile wasn't stable enought I would just use Roundcube.

ClamAV and Postfix are a must have for me so is spam assassin.

The use case is for me and some of my consultant services and my wife and her graphic design stuff.

P.S. Yes I encrypt my file system for all my machines and am getting around to my other half's

P.P.S. I prefer zypper over apt :P