We do not recommend using mapped network drives and recommend using UNC paths for network file shares due to their unreliable nature.
Network drives are typically not recognized by Windows services. This means that jobs run in the Umango service will fail.
A mapped drive looks like "Z:" and is like a virtual representation of a full UNC path.
A UNC path looks like "\\MyComputer\MySharedFolder\MySubFolder"
Link to this article http://umango.com/KB?article=46