Financial terms of the deal, disclosed Wednesday, were not announced.
Under the agreement, Xandros has received licenses for Microsoft's Exchange ActiveSync protocol and Outlook-Exchange Transport Protocol.
Implementing the former gives organizations the ability to enable mobile, over-the-air access to e-mail messages, calendars, contacts, task lists and other mailbox data. The latter will help improve protocol management between client applications and the Scalix Mail server.
Microsoft first made the Outlook-Exchange Transport protocol available for license by third parties in February. The move was widely seen as a bow to European competition watchdogs -- who've said that Microsoft needs to do more to level the playing field for rivals.
Xandros acquired Scalix -- a developer of Linux-based e-mail systems -- in July for an undisclosed sum. Company officials said access to Microsoft's Exchange protocols will help them develop a completely Linux-based enterprise stack that includes desktops, servers and management tools.
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 mixed environments.
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.