Linux distributor Xandros said it has acquired Scalix, a developer of e-mail and calendaring systems based on open source software.

Xandros said New York City-based Scalix will operate independently, as a wholly owned Xandros subsidiary. Financial terms of the deal -- disclosed Thursday -- were not announced.

Among other things, Scalix offers a Linux-based messaging system that it positions as an open source alternative to Microsoft's Exchange server. Customers include Specsavers Optical of the U.K., Sweden's Concordia Bus, and the city of Weymouth, Mass.

Xandros said the deal will not affect Scalix's existing support relationships with rival Linux operating system distributors, including Red Hat and Novell.

Xandros officials also said they do not plan to discontinue any of Scalix's offerings. "The Scalix product will continue to be developed on all platform families supported by Scalix today," said Xandros CEO Andreas Typaldos, in a statement.

Scalix officials said the deal should result in more new products for customers of both companies. "The expanded Xandros-Scalix engineering and support team will provide a truly integrated messaging and calendaring 'appliance-style' product," said Scalix CEO Glenn Winokur, in a statement.

Despite its acquisition of a developer of an Exchange alternative, Xandros also is working closely with Microsoft.

Xandros and Microsoft in June agreed to a broad set of joint technology and marketing initiatives. Among other things, the companies plan to develop software that will link Xandros' System Management tools with Microsoft's System Center -- with an eye to giving IT departments an easier way to manage heterogeneous environments.

Xandros also plans to license a set of Microsoft server communication protocols in order to make its Linux offerings more Windows-friendly.

Under the most controversial aspect of the deal, Microsoft will extend "patent covenants" to Xandros' Linux customers, waving its right to sue them for using what the company claims is Microsoft technology embedded in Linux.