How to upload mail in Windows Live to a new online account?

Hi,

I am moving my website to a new webhost and need to move all stored emails to the new IMAP server. I downloaded all emals from old online account into Windows Live. Now I want to upload (synchronize) it with online folders in my new server. These online folders in the new server so far are empty. I am afraid  if I start synchronizing them with Windows Live, all mails there will be deleted. How to make sure the synchronization will initially go only one way, i.e. to upload folders from Windows Live into online mail account rather than deleting them in Windows Live (the email address remains the same)?