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I am really curious about other people experiences and choices.

After a long scouting, I found ZCS to be a really impressive solution, maybe the only real alternative to M$ Exchange.

I'm very interested in opinions and case histories from users having already deployed Zimbra on their infrastructure or planning to do it.

Both Community and Network edition cases are appreciated, pro and cons explained too :)

Zimlets, addons, useful skins, Zimbra Desktop and other apps or mobile integration use case too of course.


locked by HopelessN00b Jan 22 '15 at 4:02

This question exists because it has historical significance, but it is not considered a good, on-topic question for this site, so please do not use it as evidence that you can ask similar questions here. This question and its answers are frozen and cannot be changed. More info: help center.

closed as off-topic by HopelessN00b Jan 22 '15 at 4:01

  • This question does not appear to be about server, networking, or related infrastructure administration within the scope defined in the help center.
If this question can be reworded to fit the rules in the help center, please edit the question.

If you are searching for an alternative to MS Exchange then you might be interested in I just leave this as a comment since it is not directly related to your question. – Raffael Luthiger Sep 2 '09 at 9:06
This question is off-topic under current topicality rules. – HopelessN00b Jan 22 '15 at 4:01
up vote 5 down vote accepted

I deployed the Network Edition of Zimbra about 15 months ago where I work. Zimbra was chosen shortly before I started so I wasn't involved in the evaluation and decision but they were looking for a solution that provided shared calendaring and mobile sync, in addition to email. And a major driving factor was that it wasn't Microsoft. I'm not sure why there is that culture here but for better or for worst I don't think Exchange was even considered due to perceived cost. Zimbra is a very good solution and we just renewed our license for another year.


  • Calendaring and resource scheduling works well.
  • With active sync it is able to push and sync email, contacts, and calendars to our phones.


  • Task management is not to the level of Exchange/Outlook
  • Dealing with attachments from a web client is not as well integrated into your OS like Outlook, so no drag and drop, etc. Their is a zimlet, Zimbra plugin, and Firefox addon that's supposed to allow for drag and drop with attachments but I have not had time to test it yet.
  • Web interface only shows 50 emails at a time and that can be a bit annoying. But the advanced search is good and it's fast.
  • Some end user training is required or users will to over look functionality that will make the transition easier like advanced search.

Another quick note.
Due to the heavy use of Java and default aggressive MySQL caching settings in Zimbra I would recommend using a system with 4GB of ram even for small deployments like ours. We serve about 50 mailboxes and we originally deployed it with 2GB of ram. In this configuration it was using about 1GB of swap and occasionally the system load would spike and the web client would display an error message saying that the server wasn't responding. Then a minute or so later things would start working again. Upgrading the server to 4GB of ram sorted out the problem.

From research it seems as though the ram requirements do not scale linearly with the number of mailboxes you're trying to serve and that you can easily serve 1000's of mailboxes with 4GB of ram. If you're doing a large deployment then I would talk with the engineers at Zimbra about what the system requirements are for your situation. You can run the different components on different servers and they would be able to help you plan and size the necessary hardware.

I'm glad this question came up because it made me check my server to see what it's uptime and memory use is. It's uptime is 206 days, not bad. But it is using about 1GB of swap currently but without the spikes in the system load or complaints from users of issues. I think I'll wait until I upgrade to 6.0, which is due out any day, to schedule the maintenance and just do a quick reboot before bringing it back online.

There are of course more pro's and con's to Zimbra than this list. So don't look at that list as if there are more con's than pro's b/c I don't think that's the case at all. That list just represents what I could think of off the top of my head. – 3dinfluence Sep 1 '09 at 19:45
You can bump the number of emails to display up to 100 (via Preferences->Mail->Display(first dropdown). But you cannot exceed 100, or disable pagination all together. – Alex Sep 2 '09 at 2:38
Yeah I keep mine set at 100 but the point is that you have to deal with the interface displaying a fixed number of emails at a time. – 3dinfluence Sep 2 '09 at 3:46
I thought I would come back and update this now that we are using 6.0.2. The mailboxes and search results are no longer broken into pages but are auto loaded, 100 at a time, as you scroll. – 3dinfluence Oct 28 '09 at 13:57
Is that 206 days without a crash or without updates too? – Bart Silverstrim Mar 18 '10 at 11:47

We have a pretty large Zimbra (Network edition) setup consisting of a multi-server, multi-site setup with 4 mailbox servers 2 MTAs and an LDAP master which supports about 30,000 users. We also have done our setup entirely on VMware. We also make use of the mobile addon for Windows phone and have the Zimbra connector for Blackberry setup on BES for Blackberry devices.

All-in-all things work very well. Some pros

  • One of our primary reasons for using it is to centralize all the data so that users don't have mail floating around on their desktops.
  • As a linux administrator, the level of things that we can script on the admin side is fantastic.
  • Setup and upgrades are easy, and we have never had an issue arise out of an update

Coming from groupwise, there are some enterprise-type features that are missing (delegating appointments, delayed send, message recall). We also had issues with the migration tool from GW->Zimbra, but that was over a year ago and we are pretty sure at least one of the issues we saw with it was from groupwise's goofy way of doing things. The biggest issue we have come up with is that people in our organization were used to using a "fat" client. When using a web client, there is a different usage pattern and people perceive things as being slower.

There have been a few bugs along the way. Nothing that has been a show-stopper, but annoyances. Their support has been good, but does leave room for some improvement. We started our installation w/ version 4.5 and have kept our installation current. After a year and a half of experience ourselves, we typically end up fixing the problems before support has an answer. On the occasions where we have been completely stuck, support has come through.

Regarding the "fat" clients, have you tried Zimbra Desktop too ? – drAlberT Sep 2 '09 at 8:19
We have a few people who are testing it out, and they have been really happy with it. Since one of our goals is to keep data off of the desktop, we have not gone forward with deploying this though. – Alex Sep 2 '09 at 13:52

We had a custom Courier/Exim setup, but most of our employees use either Outlook 2003 or 2007, and they wanted a shared environment for mail, calendars, and address books. The obvious answer was Exchange, but my boss has had some bad experiences with Exchange, and didn't relish the idea of paying that much for its functionality.

We're running ZCS 6.04 Network Edition for around 60 people, and the transition has been very smooth. Since there aren't a lot of users, I'm doing the migration myself. Installing the Outlook connector, importing items from old PSTs, and using imapsync to copy email from the old Courier server to Zimbra.

Once people start exploring what they can do, they get excited. Finally, they can use their mail, calendar, contacts, and tasks from anywhere, including mobile devices.


I used the network edition trial for a while. Its pretty slick, but in my opinion had too many bugs for primetime. One of the biggest examples is column sorting in the client. Some of the columns just wont sort. Like the "From" field. I considered that pretty important.

It does integrate with outlook well, so thats another option, but I saw a lot of the value in being able to ditch outlook.

Also - if you do a split domain setup, which allows you to migrate users one at a time to zimbra, the calendar synch isnt great.

The issues aside, they've done an excellent job. I really really wanted it to work too, so that we could ditch exchange, but some of these issues were too big to ignore.

What ZCS release are you referring? – drAlberT Sep 2 '09 at 8:17

We use zimbra for a staff of four. It works great but is a bit of resource hog. Highly recommended if you can spare the CPU cycles and RAM.


We looked at using it, and were reasonably happy with it from a technical point of view.

If you're a Microsoft shop with an Enterprise Agreement, it is very difficult and expensive to decouple the bundled server, CAL and other licenses. You can't "true down" a EA, so you have to couple your new email solution rollout to a Microsoft negotiation, which is a tough proposition. Plus, if you get a platform discount, dropping a product like Exchange will actually increase some costs.

Interesting comment, which describes very well how Microsoft uses licensing to leverage its market dominance :-/. – sleske Apr 1 '10 at 22:54

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