Battle of the Ajax Mail Packages

Scalix and Zimbra offer promising e-mail solutions that exploit Ajax to offer rich Web clients.

Traditionally, there have been two paths to choose from when considering mail servers. The Redmond path was some variety of Microsoft Exchange Server with Outlook as the client, and possibly POP3/IMAP and Web mail as a backup when out of the office.

The other path, the path of the penguin, was Sendmail or Postfix, or possibly a more obscure mail transport agent (MTA) with POP3 and IMAP as the connection to the mail client of your choice. If you wanted Web mail, you'd use a package such as SquirrelMail running under Apache. There were, of course, other choices, such as Lotus Notes, but by and large, most e-mail installations used one of these two solutions.

Recently, the e-mail landscape has changed dramatically. For one thing, rich client tools such as Gmail and Yahoo Mail have shown the promise of Ajax (Asynchronous JavaScript And XML), taking Web mail from a standby of last resort for travelers to a fully usable replacement for an e-mail application such as Outlook or Evolution. More significantly, several companies either have reached or are very close to the Holy Grail of open-source e-mail, complete Exchange compatibility.

I'm sure there are many die-hard Linux folks out there who are silently saying, “who cares?” But the reality is that in most corporate-IT environments, Outlook and Exchange are a well-entrenched aspect of the company mentality. And, it's hard to blame companies for clinging to them. The terrible twosome are full of useful features, such as meeting and calendar integration, that make them highly useful. On the other hand, it would be difficult to find a Windows sysadmin willing to describe administering an Exchange server as a pleasurable experience.

At last, these beleaguered MCSEs have a choice that doesn't involve dumping Outlook and training their employees to use an entirely new mail system. Projects such as OpenExchange, Zimbra and Scalix promise the ability to phase out Windows-based Exchange servers without the end users noticing.

Two of these projects, Scalix and Zimbra, are particularly promising because they include highly functional Ajax clients as part of their offerings. In this article, we look at the two, head to head.

Zimbra is an open-source project with a proprietary network edition, which includes features such as product support, clustering and, in the future, Outlook connectivity via MAPI. If you can make do without these features, you're free to run the open-source edition and get support in the forums. The network edition isn't cheap though, running you $28 US/user with a 500-user minimum (or $1,500 US for a 50-user small-business license). Significantly, Zimbra is still in beta, although it's well along in the development cycle.

Scalix, in comparison, is fully closed source. It offers two different versions, a community edition and an enterprise edition. As with Zimbra, the enterprise edition will cost you money, and it comes with support. The difference is that the Scalix community edition provides all the functionality of the enterprise edition. However, the advanced features, such as MAPI compatibility (which lets you use Outlook directly with the mail server for calendar and contact management), are available only for 25 users. After that, you'll be paying $60/user.

Installation Quirks

We tested both products under Fedora Core 4. For Zimbra, that and Red Hat Enterprise Linux 4 are your only official Linux choices (at least for a supported, binary install). Scalix offers those distributions as well, but adds several flavors of SUSE to the supported list. Both products install without much hair pulling; you answer a few simple questions (at least, simple if you're familiar with setting up mail servers), and the installation scripts do the rest.

At this point, I need to mention one of the irritating quirks of Zimbra. It installs its SMTP, POP3, IMAP and HTTP/HTTPS servers in high-numbered ports, and then uses iptables to map to them. So, for example, port 80 gets mapped to port 7070, where Zimbra runs its Web-mail client. This can come as a nasty surprise if you install Zimbra on a host with an existing Web server.

By comparison, Scalix keeps all its network ports off existing Web services, although it does take over mail-related ports such as SMTP and IMAP, but that's what you'd expect a mail server to do.

Scalix has its own dangers for the unwary. You had better be familiar with LDAP and how it specifies distinguished names. Scalix is all about LDAP. To be fair, Scalix is trying to operate as a drop-in replacement for Exchange, and Exchange makes heavy use of LDAP in its Active Directory architecture. So this isn't an unexpected development. However, for a sysadmin familiar with Sendmail doing a first-time install of Scalix, a close reading of the documentation is in order.

Figure 1. Both products come with a Web-based administration interface.



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MadiKL's picture

Can I migrate from AtMail to Zimbra mail server?

Zimbra / Atmail

Links forever's picture

Zibra and Atmail is beautifull and extra functionally emial clients but now i'm used Zibra because it's faster than Atmail.

Ajax in email clients is good idea.

Scalix in Los Angeles

Anonymous's picture

Scalix will be exhibiting at the 2006 Southern California Linux Expo on Feb 11-12, 2006.

What about true interoperability for Linux Clients

Alan's picture

Good review, it matched my findings when I evaluated the products, but infinitely better worded than I could ever put it.

The thing that I find is still missing is true interoperability with Linux PIM clients such as Kontact and Evolution while still offering Outlook compatibility.

My office is a mix of Windows and Linux machines running Outlook and Kontact respectively and there isn't a product that allows me to co-ordinate the various calendars, email and address books on both platforms simultaneously.


Evolution support anounced

Mephisto's picture

Hey Alan,

if you scroll down you will see that Evolution support is anounced for Scalix 10 to be released this month. Even better: The Evolution connector will be fully open source.



Not just Zimbra or Scalix

Ben Duncan's picture

Take a look at another alternative to Zimbra and Scalix called @Mail -

A product which offers a complete WebMail, Groupware & Mail-server package for Linux.

The WebMail interface includes an "Outlook" style look for IE and Firefox, including multi-language templates, Outlook Sync support for Calendar/Tasks, Shared address-book, LDAP support, SQL storage for accounts, complete Webadmin interface and more.

For a company evaluating Zimbra or Scalix, be sure to check @Mail since it provides a quality alternative.

atmail/zimbra have limited calendaring/contacts functionality

Anonymous's picture

atmail, unfortunately, doesn't have:
-the ability to view others' calendars
-notification if scheduling others conflicts w/ their calendar items
-the ability to share one's calendar w/ others.

zimbra doesn't allow one to share one's contacts w/ anyone else. that's planned in the 3rd quarter.

no, i don't work for scalix. i'm just in the process of trying to replace exchange w/ a solution that will be better than what users currently have. i haven't tested scalix yet (i'm waiting for them to send me the link to download the trial enterprise edition), otherwise i'd list things you all might find helpful.

more alternatives

Chris Jenkins's picture

atmail works quite nice and is stable. Two other groupware solutions based on ajax webtech with calendar sharing and integrated outlook support are:
- kerio
- zarafa
Both have .com sites with free downloads.

one more thing about atmail

Anonymous's picture

there's no reminder function in the calendar--even though it's running on the mail server.

Poor support from Atmail

Anonymous's picture

This thread is old, but still relevant. I bought Atmail in part based on good reviews here. The product is okay overall, but some features simply don't work and the support is just terrible. Most requests are simply ignored, others they might get back to you in a few weeks telling you to check the permissions. Then they disappear again for weeks at a time. Save your money!

That review was placed by an

Anonymous's picture

That review was placed by an employee on atmail. Atmail is still garbage support and sales wise.

I haven't been following the

Anonymous's picture

I haven't been following the development of Exchange compatible servers or webmail packages, and I was properly impressed by these two. It seems, between Firefox, OpenOffice 2.0 and these Exchange replacements, Microsoft really has something to look out for.

Why only these two?

Art's picture

These are not the only two ajax mail packages. An article of this type is not complete unless you also mention Citadel, a groupware/collaboration server of the same caliber as Zimbra and Scalix, which also contains AJAX functionality. Unlike these two, Citadel is community developed and is a true open source project. It contains AJAX webmail, a calendar and address book, and a slew of features that you won't find in any other package. Please have a look at it.


Anonymous's picture

I used Citadel as a stand-in mail server for several months, just took it down a few weeks ago.

It's a Zimbra-like system (I say that only having seen Zimbra screenshots) that's designed to act like a BBS. (That is where Citadel's roots are...if you're too young you'll have no idea what I mean.)

It was on the buggy side, but functional. I can't, however, see someone replacing an Exchange server with it though unless they have only the lightest of requirements. There were only incremental improvements to the webmail interface vs. squirrelmail. (e.g. searching; however that was one of the least functional features.)

Their support forum (on the Uncensored! Citadel) is quite active and I had all good experiences when I went there for help.

Also, I'd imagine things have changed at least a little bit since I installed.

For the record, I ended up putting money into Apple's 10.5 Server for its (well-)integrated postfix-based mail solution (and everything else...impressive feature set).

For reference:
Home site of the Citadel author(s):
Home site of the Citadel software:
To download the VMware appliance version:


P.S. If you're already an experienced Linux admin and are familiar with configuring Linux mail systems, you may have a much different (better) experience that I did. I'm fairly new at both. It was definitely easy to set up initially, but I didn't have much of a clue where to go when something wasn't working or (even worse) just wasn't working quite right.

More on Scalix

Julie Hanna Farris's picture

Great to see such a thorough review. Thanks for including our product in this roundup and for the feedback. Thought you might be interested in a preview of our latest release, Scalix 10, currently in beta and shipping in February.

- Open source connector for Novell Evolution that provides full email, calendar, contacts and public folder functionality
- Calendar interoperability between Outlook, Evolution and Scalix Web Access
- High availability solution
- Simplified installation
- Advanced web admin/mgt including mailbox size and global password management
- The ability to directly manage Scalix users and groups through Microsoft Management Console (MMC), for customers using Active Directory

A quick word about Scalix's open source strategy, which is based on a hybrid model. The Scalix Server license is not an open source license today, due to 3rd party restrictions. Specifically, Scalix's technology heritage hails from HP OpenMail. We are working to remove these restrictions so that we can open source our server. In new areas of development, like ScalixConnect for Evolution which is licensed under the GPL, we are pursuing open source licensing today.

Thanks again for the opportunity to participate in this discussion.


Update from Zimbra

John Robb's picture

Thank you for the review on our August 2005 Beta 1 Release. We at Zimbra are continuing to move our product forward based on detailed and constructive feedback like what you have provided. I wanted to offer an update on our Beta 3 Update that was just released.

1) We have removed the dependency on iptables and we have made it easier for Zimbra to co-exist with other services running on a server.

2) We have complete support for Firefox and Thunderbird 1.5 and we continue to line up our testing with new versions of these products.

3) We have released the ZCS Connector for Microsoft Outlook and it is included in the 60 day trial version of our Network Edition.

Thank you again for the help in making Zimbra better and we hope to continue to respond to your reviews.


Missing the subject?

ucntcme's picture

While I am glad to see the Citadel and atMail options, I think they were likely left out of the review because they don't appear to fit the theme. The review was not, as I understood it, about webmail clients that use AJAX, but ones *based* on it.

To me that means not using a preponderance of frames and such, but actual AJAX to update portions of the page.

Man WebCit could sure use a better interface ...