Bringing IMAP4 Capabilities and Browser-Based Mail Access to the Small Enterprise

There’s a lot to recommend about Kerio Technologies’ Kerio Mail Server, not the least of which is that it is a well-rounded mail server package priced ideally for small to midsize enterprises. However, the key to understanding Kerio Mail Server’s value is to understand and use the features built around its support for IMAP4 and Kerio’s browser-based email program, Webmail.

Most people are familiar with the ubiquitous SMTP/POP3-oriented mail programs (e.g., Microsoft Outlook and Outlook Express) that connect to a server and download each user’s mail to his or her own computer. The majority of the mail servers reviewed on ServerWatch are POP3-oriented. Although Kerio Mail Server can do POP3 services, it features IMAP4 capability, which manages the mail on the server and does not download the mail to a user’s computer. The IMAP4 approach is more centralized and thus has a tendency to focus mail services, such as anti-virus and spam control, at the server level rather than in the user’s program. It also enables Kerio’s Webmail, a browser-based program with all the usual mail functionality, and WAP connections for cell phones.

We concentrated our testing on Webmail and IMAP4 features, since they not only distinguish Kerio Mail Server but are also relatively uncommon — at least for now.

We found managing mail on a Kerio Mail Server to be somewhat slower than using POP3 software, especially on dial-up connections. However, managing mail this way also offers significant advantages. Using only a browser, a user can get mail from any computer with an Internet connection — and there are no synchronization problems. For the enterprise, there is no need to support a plethora of complex email programs. IMAP4 also makes it possible to have public mail folders (a feature commonly found on groupware servers) that are easy to set up and quite useful for sharing information on corporate projects.

One of the reasons for an organization to run its own mail server is the degree of control it provides. Kerio Mail Server capitalizes on this by focusing its security measures at the server level. Most of the individual security features are not unusual, but the package as a whole gives the mail administrator a strong feeling of control.

Unlike most other email servers, Kerio offers not one but several anti-virus options: the well-known McAfee Anti-virus for general inbound/outbound mail protection, F-Secure for Internet email, Sophos Antivirus Interface (SAVI), and Grisoft AVG 6.0 server edition. McAfee Anti-virus is integrated into the mail server; the other three are plug-ins that are easily added to the server. Kerio Mail Server can also filter email attachments based on file extension, and filter email content — although the capabilities are not as sophisticated as those of other products, such as VOP modusMail.

For general email security, Kerio Mail Server does a very good job of running in encrypted mode, which is provided by OpenSSL for POP3, SMTP, IMAP4, and Webmail. In the anti-spam department, an administrator can choose any combination of MAPS blacklisting databases: RSS, RBL, and DUL (as well as a local list) to block access for specific IP addresses. Users can be authenticated directly by IP address, through user name and password (verified by an NT Domain User List), or through authentication such as Kerberos 5. Quotas can be set on the number of emails per user, per hour and the number of connections allowed at one time.

An installation wizard handles installation and configuration of Kerio Mail Server and, as is the norm for this type of software, most installations should happen without a hitch. When its many server components are enabled, Kerio Mail Server does use a large number of ports. To avoid conflicts you probably should not run a Web server in the same computer. The MailServer Monitor (Windows only) and the Administration Console programs perform the management chores, including remote access. Both programs are utilitarian in design but are aided by excellent documentation and are quite easy to navigate and configure.

Kerio Mail Server supports a number of configuration options: dial-up, LAN, and leased-line. We particularly liked the relatively sophisticated scheduling of email send and download for dial-up connections. Kerio Mail Server can aggregate POP3 mail accounts and sort the incoming mail into separate folders (an IMAP4 feature). For more reliable downloading from other servers, the mail server supports ETRN (email transaction) triggering.

Although it’s not the most sophisticated at routing, Kerio Mail Server does support routing through mailbox aliases and groups.

User management is surprisingly strong for a product not explicitly targeted for very large enterprises. For example, user lists — which are often manually entered in other programs — can be imported from NT Domain User Lists, Microsoft Active Directory, or using WinRoute Pro. In addition, Kerio has a template system for entering standardized information for blocks of new users. All of this greatly simplifies and speeds up the onerous task of user management. There are also a number of other user friendly features, such as multilanguage support (English, Dutch, Czech, Slovak, French).

The server-centric approach to mail entailed by IMAP4 and browser-based email access should fit many corporate situations, especially where high security and control are a must. This approach is what Kerio Mail Server does best, but it’s also a full-featured SMTP/POP3 server that runs on multiple platforms, and has an attractive price. Kerio Mail Server makes a strong case for the organization deciding whether to manage its own email.

Pros: IMAP4 support, including common mail folders and browser-based access; Available for multiple platforms and in several languages.
Cons: No List server functionality; Limited firewall/proxy support.

Reviewed By: Nelson King
Original Review Date: 8/15/2002

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