Battle of the Ajax Mail Packages
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.
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.
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.