Kerio MailServer 5

Kerio MailServer is an integrated cross platform e-mail server for Windows, Solaris, Mac OS X and Linux, targeted at small to medium businesses seeking a drop-in application to look after all of their e-mail services. Its major selling points are security, integration and cross-platform accessibility.


E-mail services: The e-mail server includes an SMTP server for delivery of e-mail. Retrieval of e-mail from the server can be performed using POP3, IMAP or Web mail. WAP is also supported, allowing users to access their e-mail using a GSM mobile phone. Directory services are provided by an ActiveDirectory server. Helpful backup, server monitoring and log analysis tools are included with the configuration client.

Antispam: You would expect some level of spam protection in an integrated product such as this. The antispam options focus on preventing common exploits of the mail server such as open-relays, and filtering incoming e-mail via external antispam lists such as MAPS. Significantly, the filtering options seem to be quite limited beyond the use of an external database. It would be nice if an intelligent filtering tool such as SpamAssassin ( had been included in order to reduce the dependence of Kerio MailServer on external antispam resources.

Antivirus: Multiple external virus scanners can be used to check incoming e-mail. A range of options is available for handling e-mails that fail the virus check. A version of Kerio MailServer bundled with McAfee Antivirus is also available.

Security: All protocols supported by the server can also be used in conjunction with SSL to provide secure, encrypted communications.

Installation: The version of Kerio MailServer that I reviewed included RPMs for Red Hat Linux 7.0 only. These are a bit dated, so I attempted to install the program on the latest version of Red Hat Linux, 8.0; to my pleasant surprise, it seemed to install without hassle. The server installed itself as a normal Linux service running under xinet.d and was ready for configuration immediately. After configuration, the server operated without a hitch.


The GUI configuration component is highly accessible. An external configuration client controls all components of the e-mail server, so you can configure a Kerio MailServer installed on a Linux server from your Windows desktop. All configuration performed over a network is encrypted using SSL. Kerio boasts that a system admini­strator should be able to configure Kerio MailServer in “about 15 minutes with minimal reference to the manual”. While this statement is designed to demonstrate the ease of configuring this program, I don’t think Kerio should encourage administrators to hurry the configuration of such a security conscious product.

Kerio MailServer is organised under domains, each containing users, otherwise known as e-mail accounts. The familiar representation of this organisation is the standard e-mail address format: user@domain. Users can be organised into groups, allowing the creation of mailing lists within a domain. Each domain can be configured individually. Other options such as backup, anti-spam and virus protection are globally configured and affect all domains administered on your system.

The configuration client is easy to use and finding the settings you wish to modify is a breeze. The range of options available for configuration is a bit basic, however. Areas such as antivirus and antispam, which are sold as major features of the product, seem a bit limited.


Kerio MailServer is a solid product. Hardcore system administrators may prefer the highly flexible configuration options available in other specialised e-mail servers such as Sendmail and Exim, but those looking for a single drop-in system would do well to consider Kerio MailServer. It would be encouraging to see future versions of this program available for distributions of Linux, in addition to Red Hat Linux.

Kerio MailServer is priced under a per-user licence system. A basic version with a 20-user licence is available for $US395 from the Web site ( A 30-day trial (including McAfee Antivirus) is also available for download from the site.

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Alastair Cousins

PC World
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