I have most of my mail stored on local folders, but would like to move some of them to folders on the server (open exchange server) so I can access from other computers using webmail. When I do this, the folders I have created with em client are not showing on the webmail app. Is there some way to force synchronisation with the server?
your data should be synchronized accordingly to your sync settings in Tools>Settings>General under Synchronization.
Manual sync can be triggered by the Send and Receive button.
However if eM Client had problem synchronizing a folder, there would be an error pop up, are there any messages in Tools>Operations>Error window? If so, could you copy the third tab of this window titled Log here?