Traditional e-learning scenarios are based on a client/ server architecture and are not primarily designed for mobile scenarios. To offer e-learning in mobile scenarios, difficult technical challenges involving platform heterogeneity, wireless communication protocols, screen resolution and other usability matters must be dealt with. Ultimately, e-learning objects have to be dynamically converted and customized according to the target platform. This applies to multimedia content, as well as to the native format (e.g. XML) in which the content is stored. The "Mobile Delivery Server" (MDS) is our advanced software approach to resolve some of the problems and limitations described above. The MDS introduces a new middle layer service for the technical needs of mobile e-learning scenarios. The MDS also provides compatibility of learning objects with a broad variety of mobile clients and allows the distribution of platform dependent players.