Open source email company Scalix has released a new version of its mail server adding encryption support for Microsoft Outlook clients that eliminates the need for a VPN.

The company said that Scalix 11.3 would also focus on supporting the newest version of Outlook, including SP1, and calendaring standards that will tie in clients from Apple, Mozilla and Thunderbird.

Scalix also has added support for the CentOS operating system on an evaluation basis only.

Company officials said integration with management tools from Linux desktop and server vendor Xandros, which acquired Scalix last July, would be added to the email platform before the end of March.

Scalix is an open source mail server based on OpenMail, which runs on Linux servers, and uses email standards such as POP, IMAP, SMTP, MIME and works with any standard Lightweight Directory Access Protocol directory.

The Scalix acquisition is part of Xandros's strategy to develop a complete Linux stack, including desktop, small-to-midsize business and advanced enterprise servers, cross-platform management tools and IT infrastructure applications.

As part of the Scalix acquisition, Xandros says its BridgeWays management tools for administration, deployment/management, systems monitoring, and storage management would be adapted to manage Scalix on the platforms it supports. With the Outlook over SSL feature in Scalix 11.3 users can send encrypted e-mail between the Scalix server and Microsoft client.

Microsoft has a similar feature with Exchange Server 2007 and Outlook called Outlook Anywhere (called RPC over HTTP in earlier versions of Exchange), which also eliminates the need for a VPN connection.

Scalix also is adding support for the CalDEV standard. CalDEV is an extension of WebDav, which lets users collaboratively edit and manage files on remote web servers.

The CalDEV support means Scalix will work with Apple's Leopard client, as well as, open source Mozilla and Thunderbird clients.

"We are continuing the Scalix mission of enabling clients of choice," says Danny Essner, director of product marketing for Scalix.

Scalix competes with a host of other vendors including Linux e-mail servers from IBM, Novell and Oracle, but also with smaller email vendors such as @Mail, Gordano, IPSwitch, Kerio, Mirapoint, PostPath, Rockliffe, Sendmail, Stalker and Zimbra.