Is it possible to disable the syncing of a specific e-mail folder?

How to disable syncing of a specific folder and still sync all other folders for an account?

o.k., if you use POP3, I can’t help, but with the IMAP, gmail and exchange protocolls it is quite easy.
But be aware that in these cases there is no synching going on. Instead you can choose to show or hide the folders in question (they remain untouched on the server).
To choose folders to hide, go to the left side panel (folders) and right click on the account name (top level) and choose “Show/Hide Folders”. For every folder  under that account you then can select whether to hide it, show it or only show it, if there are unread elements.