Over the past few months we've gotten many requests for Linux Collaboration Services, which for my purposes is a solution that bundles email, calendaring, tasks, and perhaps other features. Exchange is synonymous with collaboration on Windows, but what is there in the Open Source world? This turns out to be a very good question
There are many, many, projects and commercial Linux products out there trying to fill the need for integrated email, Calendaring, tasks, etc. on Linux. Many fail to meet basic standards of stability and supportability, but choosing between what is left is still a daunting exercise. Read on or see the conclusions near the bottom for more details.
The Rejects
First let's look at the rejects: Open-Xchange, Open Groupware, Kolab, and the Bongo Project.
In the distant past I experimented with Open-Xchange provided by Spike Source, and was rather disappointed. It worked OK, but had a very picky, custom installer that would balk at anything less than a pristine CentOS4/RHEL4 install. It seems like quite the support nightmare, but unfortunately the why is missing from memory as I tried it out so long ago.
I had high hopes for Open Groupware and they have a neat easy to install option called Instant OGo, but in the end it's outdated administrative and web mail client left a bad taste in my mouth rather quickly. It gives the user the impression that it hasn't been maintained for years, whether it has or not.
Kolab installed and worked OK (on CentOS4 i386) and is by far the best fully Open Source project. Outlook support using the Toltec Connectors didn't work for me at all, but admittedly I didn't try that hard. They also use OpenPKG packages, and while cool, require compiling at install time and is different than almost every other project out there and a potential production deal breaker (in an ideal world you would not have gcc installed on any production mail server). I bet with some tweaking and support calls one could make the outlook connector work, especially on Outlook 2003.
The Bongo Project is a newer solution based on a Novell project and looks promising, but it's not ready for deployment. I had the opportunity to chat with a developer from the project at Linux Fest Northwest and he echoed that it is not ready for prime time, but that another look is warranted in the fall of 2008.
What's Left?
So where does that leave us? Zimbra and Scalix seem to be the most prudent solutions out there in this space, but as always there are downsides and question marks for both solutions.
Zimbra
Zimbra is a newer product that has a very rich web 2.0 interface that provides more than just email and calendaring. Owned by Yahoo!, Zimbra includes mapping functions, email tagging (similar to Google's Gmail). While you can use your favorite email client with Zimbra, it's clearly designed around the web interface. This can pose a problem for users who travel frequently to places without internet connections, but still need to work on email. To work around this issue, Zimbra provides a beta desktop client which is basically a stand alone version of their website that runs locally on your machine with the help of Jetty and a Java JVM. While this is a great idea, I'll exclude the local client from my conclusions here, as it's still in beta and I love stable software.
Zimbra has many other features which I don't want to get into much here as the list is long, and as I do not have extensive experience with any of them. Most noteworthy is the archiving feature that provides a native backup and restore function.
As a recently developed product (within the past few years or so), Zimbra is based on the "standard" Linux email stack including postfix, clamAV, and SpamAssasin. This is a plus for Freelock as we already administer all of these components on other servers. Thus if Zimbra breaks, we can easily look under the hood and find problems.
Scalix
The other attractive solution is Scalix, based on HP's mature OpenMail code. The first thing that caught my eye with Scalix is the excellent documentation (Zimbra's is pretty good as well). While it is a fully commerical product, Scalix offers the source code to the core product and unlike Zimbra the free community version offers many great features, including outlook support. The catch with Scalix is that you have to pay if you have more than 10 premium (Outlook) users.
Scalix installed flawlessly for me on CentOS5 64-bit and like most other commercially oriented products RedHat/CentOS and SuSE are the best supported. Props to Zimbra for supporting Debian and Ubuntu Server (my favorite).
The big deal about Scalix is that it flawlessly supports Outlook 2007. While many users are still using Outlook 2003 (latest version that Zimbra supports), it shows that Scalix is serious about supporting Microsoft users. Since I had excellent luck with Scalix and Outlook 2007, I expect few problems with other versions of Outlook, but I did not try these (usually the most recent release has the worst support).
Further extending their love to Outlook fans, Scalix's web interface is very reminicent of outlook. It is cleary the best solution for those customers who refuse to move off of Outlook, and for a better TCO than Zimbra as well. Clients moving from Exhange will find Scalix is their best option as well.
So what's not to like about Scalix? For one it's not really Open Source like other products such as Kolab, but Zimbra is more restrictive than most Open Source licenses as well. While this may hold us from pushing Scalix much, it's still a very cost effective collaboration solution. Scalix is also based on the old standard MTA, sendmail, which most Linux administrators have abandoned in favor of Postfix.
| Outlook Support | Tasks | Anti Virus | Spam Protection | Calendars | Free/busy Support | Number of Users in Free/Open Source Version | Approximate Cost for 20 Enterprise users.** | ||
| Scalix | Yes | Yes | Not Bundeled | Not Bundeled | Yes | Yes | 10 | $650 + $200/year after first year. | |
| Zimbra | Enterprise Only* | Yes | Yes | Yes | Yes | Yes | Unlimited | $625/year |
*Zimbra only supports Outlook 2003 and older, Scalix supports 2007 and older.
**Price reflects small business edition for Scalix and Zimbra standard edition without Archiving. Zimbra Enterprise edition with Outlook support is $875/year, Archiving feature adds $600/year for 25 uesrs.
Other Options
While this article focused on solutions that can be installed offsite, there are several outsourced options as well. Many companies offer Exchange hosting, which can't be beat for users needing 100% outlook computability. Several providers are offering Zimbra hosting as well. Outsourcing is a great option for small companies as the cost of deploying and maintaining another server and email software has quite a high barrier to entry. Users with higher numbers of users will likely save more deploying on site, and that's where we can help! Many customers also like the having email servers on site for performance and perceived security of their data. I say perceived security, as unless you are encrypting your mail, it's not really secure anyway.
"Rolling your own" is another option. By this I mean installing your own postfix or sendmail MTA, couier or dovecot POP3/IMAP service, etc., but this is not an exercise for the faint of heart. It requires fairly intimate knowledge of everything involved and is akin to custom software development: it can take a long time to setup and support (and time equals money). With that said, it can make sense if you have requirements outside of the norm or are hosting email for a large number of users where the cost (or time) of implementation can be spread out over the subscribed user base. If you are interested in such a setup I'd look at integrating Postfix, Dovecott, and DAViCal with OpenLDAP user accounts.
Conclusions
In summary Scalix and Zimbra are worth a test run against your requirements and hopefully the future will bring more mature open source choices.
Projects to avoid:
Projects to keep an eye on:
And the winner is...
As always, it depends. Right now Scalix seems like the clear winner for my customers, but if you are an Open Source purist Zimbra may offend you less. Zimbra may also be a choice for a new startup type company without any strings attached to Outlook, even though it's Enterprise product supports Outlook.
Finally, Zimbra includes spam and virus protection where Scalix does not. This is not a huge inconvenience for enterprise users who likely already have these in place, but can put an extra burden on the do-it-yourself small business user who just wants a working email server.
Keep in mind that both Zimbra and Scalix (not to mention most other projects mentioned previously) are best deployed on their own server. If you only have one server in your environment, this will be a problem. If you have the capacity, using virtualization technologies such as VMWare or XEN may be your best option.
I hope this post helps clear some of the muddy waters of email and calendaring solutions on Linux. Feel free to comment below or contact me via nick at freelock dot com.